Chapter 5 Resource: Motion, Forces, and Simple Machines
Transcripción
Chapter 5 Resource: Motion, Forces, and Simple Machines
Glencoe Science Chapter Resources Motion, Forces, and Simple Machines Includes: Reproducible Student Pages ASSESSMENT TRANSPARENCY ACTIVITIES ✔ Chapter Tests ✔ Section Focus Transparency Activities ✔ Chapter Review ✔ Teaching Transparency Activity ✔ Assessment Transparency Activity HANDS-ON ACTIVITIES ✔ Lab Worksheets for each Student Edition Activity Teacher Support and Planning ✔ Laboratory Activities ✔ Content Outline for Teaching ✔ Foldables–Reading and Study Skills activity sheet ✔ Spanish Resources ✔ Teacher Guide and Answers MEETING INDIVIDUAL NEEDS ✔ Directed Reading for Content Mastery ✔ Directed Reading for Content Mastery in Spanish ✔ Reinforcement ✔ Enrichment ✔ Note-taking Worksheets Glencoe Science Photo Credits Section Focus Transparency 1: UNIVERSAL PRESS SYNDICATE Section Focus Transparency 2: G. Savage/Vandtstadt/Photo Researchers Section Focus Transparency 3: Jeff Greenberg/Visuals Unlimited Teaching Transparency: (t) Lew Long/The Stock Market, (cl) Bob Daemmrich, (cr) Bob Daemmrich, (b) Gregg Otto/Visuals Unlimited Copyright © by The McGraw-Hill Companies, Inc. All rights reserved. Permission is granted to reproduce the material contained herein on the condition that such material be reproduced only for classroom use; be provided to students, teachers, and families without charge; and be used solely in conjunction with the Motion, Forces, and Simple Machines program. Any other reproduction, for use or sale, is prohibited without prior written permission of the publisher. Send all inquiries to: Glencoe/McGraw-Hill 8787 Orion Place Columbus, OH 43240-4027 ISBN 0-07-867198-1 Printed in the United States of America. 1 2 3 4 5 6 7 8 9 10 079 09 08 07 06 05 04 Table of Contents To the Teacher Reproducible Student Pages ■ iv Hands-On Activities MiniLAB: Try at Home Determining Weights in Newtons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 MiniLAB: Observing Mechanical Advantage–Pulleys. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Lab: Motion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Lab: Use the Internet Methods of Travel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Laboratory Activity 1: Speed of Falling Objects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Laboratory Activity 2: Newton’s First Law of Motion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Foldables: Reading and Study Skills . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 ■ Meeting Individual Needs Extension and Intervention Directed Reading for Content Mastery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Directed Reading for Content Mastery in Spanish . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Reinforcement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 Enrichment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 Note-taking Worksheet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 ■ Assessment Chapter Review. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 Chapter Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 ■ Transparency Activities Section Focus Transparency Activities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 Teaching Transparency Activity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 Assessment Transparency Activity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 Teacher Support and Planning Content Outline for Teaching. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . T2 Spanish Resources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . T5 Teacher Guide and Answers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . T9 Additional Assessment Resources available with Glencoe Science: • • • • • • • • • ExamView® Pro Testmaker Assessment Transparencies Performance Assessment in the Science Classroom Standardized Test Practice Booklet MindJogger Videoquizzes Vocabulary PuzzleMaker at msscience.com Interactive Chalkboard The Glencoe Science Web site at: msscience.com An interactive version of this textbook along with assessment resources are available online at: mhln.com iii To the Teacher This chapter-based booklet contains all of the resource materials to help you teach this chapter more effectively. Within you will find: Reproducible pages for ■ Student Assessment ■ Hands-on Activities ■ Meeting Individual Needs (Extension and Intervention) ■ Transparency Activities A teacher support and planning section including ■ Content Outline of the chapter ■ Spanish Resources ■ Answers and teacher notes for the worksheets Hands-On Activities Laboratory Activities: These activities do not require elaborate supplies or extensive pre-lab preparations. These student-oriented labs are designed to explore science through a stimulating yet simple and relaxed approach to each topic. Helpful comments, suggestions, and answers to all questions are provided in the Teacher Guide and Answers section. Foldables: At the beginning of each chapter there is a Foldables: Reading & Study Skills activity written by renowned educator, Dinah Zike, that provides students with a tool that they can make themselves to organize some of the information in the chapter. Students may make an organizational study fold, a cause and effect study fold, or a compare and contrast study fold, to name a few. The accompanying Foldables worksheet found in this resource booklet provides an additional resource to help students demonstrate their grasp of the concepts. The worksheet may contain titles, subtitles, text, or graphics students need to complete the study fold. Meeting Individual Needs (Extension and Intervention) Directed Reading for Content Mastery: These worksheets are designed to provide students with learning difficulties with an aid to learning and understanding the vocabulary and major concepts of each chapter. The Content Mastery worksheets contain a variety of formats to engage students as they master the basics of the chapter. Answers are provided in the Teacher Guide and Answers section. iv Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc. MiniLAB and Lab Worksheets: Each of these worksheets is an expanded version of each lab and MiniLAB found in the Student Edition. The materials lists, procedures, and questions are repeated so that students do not need their texts open during the lab. Write-on rules are included for any questions. Tables/charts/graphs are often included for students to record their observations. Additional lab preparation information is provided in the Teacher Guide and Answers section. Directed Reading for Content Mastery (in Spanish): A Spanish version of the Directed Reading for Content Mastery is provided for those Spanish-speaking students who are learning English. Reinforcement: These worksheets provide an additional resource for reviewing the concepts of the chapter. There is one worksheet for each section, or lesson, of the chapter. The Reinforcement worksheets are designed to focus primarily on science content and less on vocabulary, although knowledge of the section vocabulary supports understanding of the content. The worksheets are designed for the full range of students; however, they will be more challenging for your lower-ability students. Answers are provided in the Teacher Guide and Answers section. Enrichment: These worksheets are directed toward above-average students and allow them to explore further the information and concepts introduced in the section. A variety of formats are used for these worksheets: readings to analyze; problems to solve; diagrams to examine and analyze; or a simple activity or lab which students can complete in the classroom or at home. Answers are provided in the Teacher Guide and Answers section. Note-taking Worksheet: The Note-taking Worksheet mirrors the content contained in the teacher version—Content Outline for Teaching. They can be used to allow students to take notes during class, as an additional review of the material in the chapter, or as study notes for students who have been absent. Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc. Assessment Chapter Review: These worksheets prepare students for the chapter test. The Chapter Review worksheets cover all major vocabulary, concepts, and objectives of the chapter. The first part is a vocabulary review and the second part is a concept review. Answers and objective correlations are provided in the Teacher Guide and Answers section. Chapter Test: The Chapter Test requires students to use process skills and understand content. Although all questions involve memory to some degree, you will find that your students will need to discover relationships among facts and concepts in some questions, and to use higher levels of critical thinking to apply concepts in other questions. Each chapter test normally consists of four parts: Testing Concepts measures recall and recognition of vocabulary and facts in the chapter; Understanding Concepts requires interpreting information and more comprehension than recognition and recall—students will interpret basic information and demonstrate their ability to determine relationships among facts, generalizations, definitions, and skills; Applying Concepts calls for the highest level of comprehension and inference; Writing Skills requires students to define or describe concepts in multiple sentence answers. Answers and objective correlations are provided in the Teacher Guide and Answers section. Transparency Activities Section Focus Transparencies: These transparencies are designed to generate interest and focus students’ attention on the topics presented in the sections and/or to assess prior knowledge. There is a transparency for each section, or lesson, in the Student Edition. The reproducible student masters are located in the Transparency Activities section. The teacher material, located in the Teacher Guide and Answers section, includes Transparency Teaching Tips, a Content Background section, and Answers for each transparency. v Teaching Transparencies: These transparencies relate to major concepts that will benefit from an extra visual learning aid. Most of these transparencies contain diagrams/photos from the Student Edition. There is one Teaching Transparency for each chapter. The Teaching Transparency Activity includes a black-and-white reproducible master of the transparency accompanied by a student worksheet that reviews the concept shown in the transparency. These masters are found in the Transparency Activities section. The teacher material includes Transparency Teaching Tips, a Reteaching Suggestion, Extensions, and Answers to Student Worksheet. This teacher material is located in the Teacher Guide and Answers section. Assessment Transparencies: An Assessment Transparency extends the chapter content and gives students the opportunity to practice interpreting and analyzing data presented in charts, graphs, and tables. Test-taking tips that help prepare students for success on standardized tests and answers to questions on the transparencies are provided in the Teacher Guide and Answers section. Teacher Support and Planning Content Outline for Teaching: These pages provide a synopsis of the chapter by section, including suggested discussion questions. Also included are the terms that fill in the blanks in the students’ Note-taking Worksheets. Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc. Spanish Resources: A Spanish version of the following chapter features are included in this section: objectives, vocabulary words and definitions, a chapter purpose, the chapter Activities, and content overviews for each section of the chapter. vi Reproducible Student Pages Reproducible Student Pages ■ Hands-On Activities MiniLAB: Try at Home Determining Weights in Newtons . . . . . . . . . . 3 MiniLAB: Observing Mechanical Advantage–Pulleys. . . . . . . . . . . . . . . 4 Lab: Motion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Lab: Use the Internet Methods of Travel . . . . . . . . . . . . . . . . . . . . . . . . . 7 Laboratory Activity 1: Speed of Falling Objects . . . . . . . . . . . . . . . . . . . 9 Laboratory Activity 2: Newton’s First Law of Motion . . . . . . . . . . . . . 13 Foldables: Reading and Study Skills . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 ■ Meeting Individual Needs Extension and Intervention Directed Reading for Content Mastery . . . . . . . . . . . . . . . . . . . . . . . . 17 Directed Reading for Content Mastery in Spanish . . . . . . . . . . . . . . . 21 Reinforcement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 Enrichment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 Note-taking Worksheet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 ■ Assessment Chapter Review. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 Chapter Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 ■ Transparency Activities Section Focus Transparency Activities . . . . . . . . . . . . . . . . . . . . . . . . . 42 Teaching Transparency Activity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 Assessment Transparency Activity . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 Motion, Forces, and Simple Machines 1 Hands-On Activities Hands-On Activities 2 Motion, Forces, and Simple Machines Date Class Hands-On Activities Name Determining Weights in Newtons Procedure 1. Stand on a bathroom scale and measure your weight. 2. Hold a large book, stand on the scale, and measure the combined weight of you and the book. Record your data in the table below. 3. Repeat step 2 using a chair, heavy coat, and a fourth object of your choice. Data and Observations Pounds Newtons My weight My weight with a book My weight with a chair My weight with a coat Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc. My weight with a ____________ Analysis 1. Subtract your weight from each of the combined weights to calculate the weight of each object in pounds. 2. Multiply the weight of each object in pounds by 4.4 to calculate its weight in newtons. 3. Calculate your own weight in newtons. Motion, Forces, and Simple Machines 3 Name Date Class Procedure 1. Tie a 3-m-long rope to the middle of a broomstick or dowel and hold this stick horizontally. Another student should hold another stick horizontally. Wrap the rope around both sticks four times, leaving about 0.5 m between the sticks. 2. A third student should pull on the rope while the other two students try to keep the sticks from coming closer together. 3. Observe what happens. Repeat using only two wraps of the rope and then using eight wraps. Analysis 1. Describe what you observed. Could the students hold the sticks apart? 2. Compare and contrast the results with two, four, and eight turns of the rope around the sticks. Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc. Hands-On Activities Observing Mechanical Advantage—Pulleys 4 Motion, Forces, and Simple Machines Name Date Class Hands-On Activities Motion Lab Preview Directions: Answer these questions before you begin the Lab. 1. Should you conduct this lab on a flat surface or on a hill? 2. For how long should you record the distance traveled by the ball at 1-s intervals? What happens when you roll a small ball down a ramp? It speeds up as it travels down the ramp, and then it rolls across the floor and eventually it stops. You know that as the ball travels down the ramp, gravity is acting to make it speed up. Think about the forces that are acting on the ball as it rolls across the floor. Is there a net force acting on the ball? How would you describe the motion of the ball? Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc. Real-World Question How does a ball move when the forces acting on it are balanced and when they are unbalanced? Materials small ball or marble stopwatch meterstick or tape measure graph paper Goals ■ ■ Demonstrate the motion of a ball with balanced and unbalanced forces acting on it. Graph the position versus time for the motion of the ball. Safety Precautions Procedure 1. Place the ball on the floor or a smooth, flat surface. 2. Roll the ball across the floor by giving it a gentle push. 3. Record Data As the ball is rolling and no longer being pushed, have one student keep track of the time and have other students record the distance at 1-s intervals for at least 5 s to 10 s. 4. Record anything else that you observed about how the ball moved. 5. Calculate from your data the distance the ball has traveled at each second. 6. Make a graph of the distance the ball travels versus time. Plot the distance traveled on the vertical y-axis and the time on the horizontal x-axis. 7. Choose three one-second time intervals. Calculate the speed of the ball in each of those time intervals. Motion, Forces, and Simple Machines 5 Name Date Class (continued) Conclude and Apply 1. Describe how the speed of the ball changes as it rolls along the floor. 2. Describe the forces acting on the ball before you pushed it and it was at rest. Infer whether the forces acting on the ball were balanced or unbalanced. 3. Describe the forces acting on the ball as it rolled across the floor. Infer whether the forces acting on the ball were balanced or unbalanced. Communicating Your Data Compare your graphs and results with those of other students in your class. 6 Motion, Forces, and Simple Machines Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc. Hands-On Activities Data and Observations Name Date Class Use the Internet Hands-On Activities Methods of Travel How long does it take you to get to the other side of town? How long does it take to get to the other side of the country? If you were planning a road trip from New York City to Los Angeles, how long would it take? How would your trip change if you flew instead? When you plan a trip or vacation, it is useful to first estimate your travel time. Travel time depends on the vehicle you use, how fast you travel, the route you take, and even the terrain. For example, driving over rugged mountains can take longer than driving over flat farmland. With this information, you can plan your trip so you arrive at your final destination on time. Form a hypothesis about what is the fastest form of travel. Real-World Question Make a Plan What’s the fastest way to travel between two specific locations? 1. Choose a starting point and a final destination. 2. Identify the routes commonly used between these two locations. 3. Determine the common forms of travel between these two locations. 4. Research how to estimate travel time. What factors can make your trip take more or less time? Goals ■ ■ Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc. ■ ■ Research travel times. Compare travel times for different methods of travel. Evaluate the fastest way to travel between two locations. Design a table to display your findings and communicate them to other students. Data Source SCIENCEOnline Go to the Glencoe Science Web site at msscience.com for more information on travel times, methods of travel, distances between locations, and data from other students. Follow Your Plan 1. Make sure your teacher approves your plan before you start. 2. Calculate the travel time and distance between your two locations for different methods of travel. 3. Record your data on a separate sheet of paper. Analyze Your Data 1. Analyze the data recorded to determine the fastest method of travel. Was it better to drive or fly? Did you investigate another method of travel? Motion, Forces, and Simple Machines 7 Name Date Class (continued) 3. Organize Data Use a computer (home, library, or computer lab) to create a chart that compares the travel times, average speeds, and distances for different methods of travel. Use your chart to determine the fastest method of travel. What factors add to travel time? Conclude and Apply 1. Compare your findings to those of your classmates and data posted on the Glencoe Science Web site. What is the greatest distance investigated? The shortest? 2. Draw Conclusions What factors can affect travel time for the different methods? How would your travel time be different if you didn’t have a direct flight? 3. Infer how the average speed of an airplane flight would change if you included your trips to and from the airport and waiting time in your total travel time. Communicating Your Data Find this lab using the link below. Post your data in the table provided. Combine your data with those of other students and make a class travel booklet that estimates travel times for various locations around the world. msscience.com 8 Motion, Forces, and Simple Machines Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc. Hands-On Activities 2. Calculate the average speed of the methods of travel you investigated. Which method had the fastest speed? Which method had the slowest? Date 1 Laboratory Activity Class Speed of Falling Objects Galileo attempted to prove that objects of different mass will reach the ground at the same time when dropped from the same height. But this was difficult, since the objects fell so quickly he couldn’t tell whether or not they actually hit the ground together. Galileo thought that if he could slow down the objects, he would be able to make more accurate observations. Strategy You will show the speeds of falling objects of different mass. You will compare the speeds of falling objects of different mass. Materials masking tape 15 cm × 150 cm gutter *15 cm × 150 cm board with sides chair 2 marbles (each of different mass) index card 9. Exchange the position of the marbles at the starting line and run the experiment three more times (six times in all). Record your results. 10. Repeat the experiment placing the gutter at a different angle to the floor. Record your results in Table 2. Figure 1 *Alternate Materials Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc. Procedure 1. Place a strip of masking tape straight across each end of the gutter (one near each end of the board). See Figure 1. 2. Rest one end of the gutter on top of the back of the chair. (The top of the gutter should be at shoulder height or higher.) See Figure 1. 3. Place both marbles on one edge of the tape at the top of the gutter. This is the starting line. 4. Have your partner position himself or herself near the tape at the bottom. This is the finish line. 5. Hold an index card in front of the marbles. Raise it to release both marbles at the same time. 6. Have your partner watch to see the order in which the marbles cross the finish line. 7. Record the results by putting a checkmark in the appropriate column in Table 1 in the Data and Observations section. 8. Repeat the experiment two more times with the marbles positioned as in step 3. Motion, Forces, and Simple Machines 9 Hands-On Activities Name Name Date Class Laboratory Activity 1 (continued) Table 1 Slope _________________________ Trial Large marble went faster Small marble went faster Both went at same speed 1 2 3 4 5 6 Table 2 Slope _________________________ Trial Large marble went faster Small marble went faster Both went at same speed 1 2 3 4 5 6 Questions and Conclusions 1. How do the speeds of the rolling marbles compare? 2. Was there any difference in speed after you exchanged positions of the marbles? 10 Motion, Forces, and Simple Machines Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc. Hands-On Activities Data and Observations Name Date Class Hands-On Activities Laboratory Activity 1 (continued) 3. Why might it be important to change the position of the marbles for one half of the trials? 4. Compare and contrast your results with the ramp at different angles. 5. What can you conclude about the speed of falling objects of different mass? Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc. 6. Compare and contrast the motion of marbles rolling down the ramp with the motion of marbles that are dropped. Strategy Check Can you show the speeds of falling objects of different mass? Can you compare the speeds of falling objects of different mass? Motion, Forces, and Simple Machines 11 Date 2 Laboratory Activity Class Newton’s First Law of Motion One of Isaac Newton’s laws of motion states that all bodies at rest tend to remain at rest unless a force acts on them. However, once a body is set in motion by an outside force, the body moves in a straight line until another force causes it to change speed or direction. The force that changes the motion of the body may be air pressure, friction, or another body. Strategy You will measure the amount of force needed to set a body in motion. You will deduce the relationship between the force needed to start a body in motion and the mass of the body. Materials balance bricks spring scale Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc. Procedure 1. Determine the mass of one brick. Record it in Table 1. 2. Attach the brick to the spring scale. Pull the brick slowly across the floor. 3. Record the force needed to start the brick in motion. Record the force needed to keep the brick in motion. 4. Determine the mass of the second brick. Add that to the mass of the first brick and record it in Table 1. 5. Repeat steps 2 and 3 with the second brick on top of the first brick. 6. Determine the mass of the third brick. Add that to the mass of the other bricks and record it in Table 1. 7. Repeat steps 2 and 3 with the third brick on top of the other two bricks. Data and Observations Table 1 Number of bricks Force (N) Mass (kg) Start Keep in motion 1 2 3 Motion, Forces, and Simple Machines 13 Hands-On Activities Name Name Date Class Laboratory Activity 2 (continued) 1. What is the outside force that starts the brick(s) in motion? 2. Compare the force needed to start the brick(s) in motion and the force needed to keep the brick(s) in motion. 3. Compare the force required to keep the brick(s) in motion to the mass of the brick(s). 4. State the relationship between the force needed to start a body in motion and the body’s mass. 5. What force resists the motion of the bricks in all cases? 6. Explain in terms of Newton’s law of motion what happens to a passenger who is standing in the aisle of a bus when the bus stops suddenly. Use diagrams to help explain your answer. Strategy Check Can you measure the amount of force needed to set a body in motion? Can you state the relationship between the force needed to start a body in motion and the mass of the body? 14 Motion, Forces, and Simple Machines Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc. Hands-On Activities Questions and Conclusions Name Date Class Hands-On Activities Motion, Forces, and Simple Machines Directions: Use this page to label your Foldable at the beginning of the chapter. Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc. Know Want Learned Motion, Forces, and Simple Machines 15 Meeting Individual Needs Meeting Individual Needs 16 Motion, Forces, and Simple Machines Name Date Directed Reading for Content Mastery Class Overview Motion, Forces, and Simple Machines Meeting Individual Needs Directions: Use the formula v = d/t to answer the following question. 1. Julio rides his bike 12 km in 1.5 h. Determine the average speed at which Julio rode. Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc. Directions: The figure below illustrates Newton’s third law of motion. Use it to answer the questions below. 2. Draw arrows on the figure above to show the direction in which the oars must move to send the boat forward. 3. Do the arrows you drew in the figure represent an action force or a reaction force? Directions: Answer the following question about weight. 4. If your weight is 490 N and you stand on a box that exerts a normal force of 440 N, what will happen? Directions: Answer the following question on the lines provided. 5. A third-class lever has a mechanical advantage of less than one. Why are thirdclass levers used if this is the case? Motion, Forces, and Simple Machines 17 Name Date Directed Reading for Content Mastery Section 1 Section 2 ■ ■ Class Motion Newton’s Laws of Motion Directions: Study the following diagram. Then answer questions 1 and 2 on the lines provided. C 50 m 90 m D 70 m 120 m A 1. What distance will John travel if he goes from A to B to C to D and back again to A? 2. If John covers the distance in two minutes, what is his average speed in meters per minute? Directions: Write speed or acceleration to indicate what each unit below measures. 3. m/s 4. km/h 5. m/s/s Directions: Fill in the blanks in the chart below. Newton’s Laws of Motion An object at rest will remain at rest or an object moving straight at constant First law speed will continue this motion until a 6. ____________________ acts on it. An object that has a force acting on it will 7. ___________________ in the Second law direction of the force. Third law Forces always occur in equal but 8. ___________________ pairs. 18 Motion, Forces, and Simple Machines Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc. Meeting Individual Needs B Name Date Directed Reading for Content Mastery Section 3 ■ Class Work and Simple Machines Directions: Use the clues below to complete the puzzle. Across 2. A machine that uses only one movement 4. The force you apply when using a machine 5. Probably the first simple machine Meeting Individual Needs Down 1. Work = force × _______ 3. Inclined _______; ramp Directions: Place a check mark (✓) next to each statement that is true. If the statement is false, rewrite the statement to make it true. Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc. 1. In order for you to do work, you only need to apply force to an object. 2. A simple machine is one that always gives a mechanical advantage of 2. 3. Force can be expressed in units called newtons. 4. An inclined plane allows you to lift a heavy load by using greater force over less distance. Motion, Forces, and Simple Machines 19 Name Date Directed Reading for Content Mastery Class Key Terms Motion, Forces, and Simple Machines Directions: Use the following terms to complete the sentences below. joules motion output force friction acceleration force average speed velocity lever net force 1. A push or a pull is a(n) ______________________________. 3. ______________________________ equals change in speed divided by time. 4. ______________________________ changes when speed changes, direction of motion changes, or both factors change. 5. Work, like energy, is measured in ______________________________. 6. Mechanical advantage equals ______________________________ divided by effort force. 7. ______________________________ equals total distance traveled divided by travel time. 8. ______________________________ is a force that resists motion between two surfaces that are in contact. 9. Probably the first simple machine invented by prehistoric humans was the ______________________________. 10. The combination of all forces acting on an object is the ______________________________. 20 Motion, Forces, and Simple Machines Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc. Meeting Individual Needs 2. Newton’s laws explain ______________________________. Nombre Fecha Lectura dirigida para Dominio del contenidio Clase Sinopsis Movimiento, fuerzas y máquinas simples Satisface las necesidades individuales Instrucciones : Usa la fórmula v = d/t para contestar la siguiente pregunta. 1. Julio anda en bicicleta 12 km en 1.5 h. Determina la rapidez promedio de Julio en esta travesía. Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc. Instrucciones: La figura ilustra la tercera ley del movimiento de Newton. Úsala para contestar las preguntas. 2. Dibuja flechas en la figura que muestren la dirección en que deben moverse los remos para que el bote avance. 3. ¿Representan una fuerza de acción o una fuerza de reacción las flechas que dibujaste? Instrucciones: Contesta estas preguntas sobre el peso. 4. Si pesas 490N y estás parado sobre una caja que ejerce una fuerza normal de 440N, ¿qué sucederá? Instrucciones: Contesta esta pregunta. 5. Una palanca de tercera clase tiene una ventaja mecánica de menos de uno. Si es así, ¿por qué usamos palancas de tercera clase? Movimiento, fuerzas y máquinas simples 21 Nombre Fecha Lectura dirigida para Dominio del contenidio Sección 1 Sección 2 Clase ■ ■ El movimiento Las leyes del movimiento de Newton Instrucciones : Estudia el diagrama. Contesta luego las preguntas 1 y 2 en los espacios dados. C 50 m B 70 m 120 m A 1. ¿Qué distancia viajará John si va de A a B a C a D y de regreso a A? 2. Si John cubre esa distancia en dos minutos, ¿cuál es su velocidad promedio en metros por minuto? Instrucciones: Escribe velocidad o aceleración para indicar lo que mide cada unidad. 3. m/s 4. km/h 5. m/s/s Instrucciones: Llena los espacios en blanco de la tabla. Leyes del movimiento de Newton Primera ley Un cuerpo en reposo permanecerá en reposo y un cuerpo que se mueve en línea recta a velocidad constante continuará este movimiento hasta que un(a) 6. ____________________ actúe sobre él. Segunda ley Un objeto que experimenta una fuerza actuando sobre él se 7. ___________________ en la dirección de la fuerza. Tercera ley Las fuerzas siempre ocurren en pares iguales pero 8. ___________________. 22 Movimiento, fuerzas y máquinas simples Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc. Satisface las necesidades individuales 90 m D Nombre Fecha Lectura dirigida para Sección 3 Dominio del contenidio Clase ■ Trabajo y máquinas simples Instrucciones : Usa las claves para completar el crucigrama. 1 3. Máquina que usa un solo movimiento 3 4. La fuerza que aplicas cuando usas una máquina 2 Satisface las necesidades individuales Horizontales 2. _______ inclinado; rampa 4 Verticales 1. Trabajo = fuerza × _______ 2. Probablemente la primera máquina simple Instrucciones: Marca con una X la afirmación verdadera. Si la afirmación es falsa, vuelve a escribir la afirmación en forma correcta en las líneas dadas. Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc. 1. Para realizar trabajo, sólo necesitas aplicarle una fuerza a un cuerpo. 2. Una máquina simple es aquella que siempre da una ventaja mecánica de dos. 3. La fuerza puede expresarse en unidades llamadas newtons. 4. Un plano inclinado permite levantar objetos pesados usando más fuerza en una distancia más corta. Motion, Forces, and Simple Machines 23 Nombre Fecha Lectura dirigida para Dominio del contenidio Clase Términos claves Movimiento, fuerzas y máquinas simples Instrucciones: Usa estos términos para completar las siguientes oraciones. julios fuerza de salida fuerza palanca movimiento fricción velocidad promedio fuerza neta velocidad 1. Un empujón o un jalón es un(a) ______________________________. 2. Las leyes de Newton explican ______________________________. 3. El(La) ______________________________ es igual al cambio en velocidad dividido por el tiempo. 4. El(La) ______________________________ cambia cuando cambia la velocidad, cuando cambia la dirección del movimiento, o cuando ambos(as) cambian. 5. Al igual que la energía, el trabajo se mide en ______________________________. 6. La ventaja mecánica es igual a ______________________________ dividida por la fuerza de esfuerzo. 7. El(La) ______________________________ es igual a la distancia total recorrida dividida por el tiempo de viaje. 8. El(La) ______________________________ es la fuerza que resiste el movimiento entre dos superficies en contacto. 9. Es posible que la primera máquina simple que inventaron los humanos prehistóricos haya sido el(la) ______________________________. 10. La combinación de todas las fuerzas que actúan sobre un cuerpo es el(la) _____________________________. 24 Movimiento, fuerzas y máquinas simples Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc. Satisface las necesidades individuales aceleración Name 1 Date Reinforcement Class Motion Directions: Identify what each of the following formulas is used to find. 1. (change in speed)/time 2. acceleration × time Meeting Individual Needs 3. (total distance traveled)/time 4. 1/2 (acceleration)(time)2 Directions: The graph shows the various speeds at which a worm travels over a 10-minute interval. Use the graph to answer the questions that follow. 5. What is the greatest speed the worm reaches? Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc. 6. What is the worm’s acceleration during the first 2 minutes? 7. How fast is the worm traveling as it goes from A to B? 8. How far does the worm travel from A to B? 9. What is the worm’s acceleration from A to B? 10. How does the worm’s motion change from B to C? 11. What is the worm’s acceleration during the last 2 minutes? 12. How would you describe the worm’s motion during the last 2 minutes? 13. How far does the worm travel during the last 2 minutes? Motion, Forces, and Simple Machines 25 Name 2 Date Reinforcement Class Newton’s Laws of Motion Directions: A yo-yo with a mass 0.25 kg is suspended from a hook on a ceiling. Use the diagram at the bottom of the page to answer the questions. 1. Identify which of Newton’s laws explains what happens in each of the following steps. a. Earth pulls the yo-yo downward and the yo-yo pulls Earth upward. b. The yo-yo doesn’t move. d. The yo-yo keeps swinging back and forth. e. The yo-yo slows down and eventually stops. f. The yo-yo pulls on the hook and the hook pulls on the yo-yo. 2. What is the net force acting on the yo-yo in step b? 3. In step e, what force causes the yo-yo to slow down and stop? 4. If a net force of 0.2 N is applied in step c, use the space below to calculate how fast the yo-yo accelerates. 5. If the same net force is applied to a yo-yo with a mass of 0.5 kg, how will the rate of acceleration be affected? Why? 6. If the hook exerts a force of 0.001 N on the ceiling, how much force does the ceiling exert on the hook? 26 Motion, Forces, and Simple Machines Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc. Meeting Individual Needs c. Someone pushes on the yo-yo in the direction shown by the arrow, and the yo-yo moves. Name 3 Date Class Work and Simple Machines Reinforcement 1. ____________________ 2. ____________________ Meeting Individual Needs Directions: Describe what is happening in each situation as work or no work. 3. ____________________ Directions: Name two situations in which no work is done to an object. 4. 5. Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc. Directions: Answer the following questions on the lines provided. 6. What two things must occur for effort to count as work? 7. How is work measured? 8. What is mechanical advantage? 9. How do the three classes of levers differ? 10. How does a pulley make work easier if it doesn’t multiply force? Motion, Forces, and Simple Machines 27 Name 1 Date Enrichment Class The Art of Motion Think back to the last time you read a comic book or saw a cartoon in the newspaper. Chances are that somewhere in that comic strip, the cartoonist showed a character in motion. Do you remember how it was done? Perhaps the cartoonist inserted horizontal lines to show motion. Maybe the cartoonist altered the actual shape of an object. List three techniques for showing motion in cartoons. 1. 3. Directions: Using simple figures, motion lines, or other techniques, draw three cartoon panels of two automobiles on a highway. One is moving at a constant speed and one is accelerating. 4. What formulas did your cartoon illustrate? 28 Motion, Forces, and Simple Machines Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc. Meeting Individual Needs 2. Name Enrichment The Physics of Hitting a Baseball What does Newton have to do with hitting a powerful homerun or line drive? According to Alan Nathan, a physicist from the University of Illinois, understanding the laws of physics can help batters improve their skill. Some people believe that physical strength can help send a ball sailing over the fence. Others believe that hitting the ball with the “sweet spot” of the bat, the place where batters feel almost no vibration after a hit, is the best way to score a home run. The laws of physics, however, prove both theories to be false. When ball meets bat, the impact from the bat reverses the direction of the ball. Nathan recommends imagining the ball as a spring and the force between the bat and ball compressing and then expanding, sending the ball flying. However, the impact is extremely brief—less than one-thousandth of a second. In that time, some energy is lost to friction. A Bigger Bat Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc. Class In addition, because of the law of actionreaction, the ball exerts an opposite force on the bat, causing the bat to move backward and taking energy away from the spring motion of the ball. Because of this fact, Nathan recommends using a heavier bat in order to offset the backward movement after impact. Furthermore, the impact causes some energy to travel as vibrations along the wood or aluminum. Interestingly, the “sweet spot” that many batters prefer because it causes the least amount of vibration is not the ideal spot to use for hitting the ball. Finding the “Best Spot” To find the best spot for hitting a baseball, Nathan used a computer to perform calculations—formulas used to analyze the vibration of airplane wings or bridges. The ideal spot he was searching for would have to account not only for vibrations, however, but also for the circular motion of the bat as it strikes. That motion increases the speed of the ball. The results of his calculations are that with a 34inch bat, the best point of impact is about six inches from the tip. With the help of another researcher, Nathan was able to test his results and found them to be accurate. Incidentally, physical strength cannot help at this point in the activity. All that matters, according to the laws of physics, is the moment and point of impact. Nathan states that “if the batter could let go of the bat just prior to hitting the ball, there would be no noticeable effect. The ball would respond in exactly the same way.” Given these findings, perhaps spring training will one day include some work in the physics lab. 1. Which of Newton’s laws causes the bat to move back from the point of impact? 2. How do Newton’s other laws apply to this situation? 3. How might studying physics help people improve performance in other sports? Motion, Forces, and Simple Machines 29 Meeting Individual Needs 2 Date Name Date Bicycle Improvements Enrichment Meeting Individual Needs The first bicycles did not have multiple gears for ease of riding. Cyclists worked hard to cover ground. They sat over the front wheel because the pedals were attached directly to the wheel’s axle. Rotating the pedals once around moved the front wheel only one complete revolution. The invention of the chain drive allowed the rider to sit in a safer, more balanced position between the front and back wheels. Gears Later, the addition of gears with varying ratios made it easier to ride up steep inclines and pedal more efficiently. Gear ratios are figured by dividing the number of teeth in the front sprocket by the number of teeth in the rear sprocket. If there are 54 teeth in front and 27 in back, the ratio is 2 to 1 because 54 ÷ 27 = 2. This means that the rear sprocket goes around twice each time the rider moves the chain ring one complete revolution. If the rear sprocket has 13 teeth, the ratio is about 4 to 1. One turn of the pedals will rotate the back sprocket four times. On downhills or level ground, a rider doesn’t have to work as hard to move the bicycle in the “fourth” gear as in the “second.” On the other hand, the steeper the incline, the more difficult it is to ride a bike in a high gear (think of lifting a heavy object straight up instead of pushing it along a ramp). In this case the rider’s goal is to easily turn the pedals several times before the rear sprocket completes a revolution. The rider needs to shift into a lower gear. Chain Drives Chain drives transfer the power from the rider’s legs, which push down on the pedals attached to levers (the cranks), which turn the axle of the toothed wheel (front sprocket, or chain ring). The chain is a continuous loop attached to the chain ring and a rear sprocket. As the chain ring rotates, it moves the chain, which moves the rear sprocket, which turns the rear wheel’s axle. Thus, the invention of the chain drive meant that a rider propelled the bike forward by moving the rear wheel, not the front one. If you think chain drives resemble pulley systems, you’re right! Directions: Complete the table below by computing the gear ratios (round to the nearest whole number). Table 1 Gear Number of teeth in rear sprocket Number of teeth in front sprocket a 11 60 1. b 22 54 2. c 41 84 3. d 60 54 4. Gear ratio 5. Which gear would be best for riding up a steep hill? Explain. 30 Motion, Forces, and Simple Machines Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc. 3 Class Name Date Note-taking Worksheet Section 1 Class Motion, Forces, and Simple Machines Motion A. ______________ involves distance and time. 1. ________________ speed—calculated as total distance traveled divided by travel time 2. ______________________ speed—an object’s speed at a particular moment 3. When instantaneous speed does not change, an object is moving at _________________ 4. Distance can be calculated if an object is moving at constant speed over a particular time period; total distance traveled equals ______________________ times time. B. Speed and direction of motion is _________________. C. _____________________ is the change in velocity divided by the time needed for the change to occur. 1. Acceleration can be calculated using a formula: acceleration equals change in ______________ divided by time. Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc. 2. Acceleration can be shown on a speed-time graph. Section 2 Newton’s Laws of Motion A. ______________—a push or a pull 1. When a force acts on an object, it ________________ the object’s acceleration. 2. Two or more forces that cancel each other out are _________________ forces. 3. Two or more forces that do not cancel each other out are ___________________ forces. 4. The combination of all forces acting on an object is the ____________ force. B. Newton’s _______________________—explain how forces cause motion 1. Newton’s first law—a moving object moves in a straight line with _________________ speed unless a force acts on it. a. _________________—a force that resists movement between two surfaces in contact b. An object’s tendency to resist a change in motion is ________________; the more mass an object has, the greater its inertia. Motion, Forces, and Simple Machines 31 Meeting Individual Needs speed; average speed and instantaneous speed are the _____________ in this situation. Name Date Class Note-taking Worksheet (continued) 2. Newton’s second law—if an object is acted upon by a ____________ force, the change in velocity will be in the direction of the ____________ force; acceleration can be calculated as acceleration equals net force divided by mass. 3. Newton’s third law—forces always occur in equal but _________________ pairs; the equal and opposite forces act on different objects, so they are not balanced forces. Section 3 Work and Simple Machines 1. Occurs when a force causes an object to move in the same direction that the force is applied 2. Calculated as work equals ______________ times distance B. A _______________ machine uses only one movement; a _________________ machine is a combination of simple machines. 1. Mechanical __________________ is the number of times force is multiplied; calculated as mechanical advantage equals output force divided by input force. 2. An ______________ machine would experience no friction, so work in would equal work out. 3. _____________ machines do experience friction, so work out is always less than work in. C. ________________—an object with a groove, like a wheel, with a rope or chain running through the groove; changes the direction of the input force D. A lever is a rod or plank that pivots about a fixed point called the ________________. 1. The fulcrum is between the input force and the output force in a ____________________ lever. 2. In a _____________________ lever, the output force is between the input force and the fulcrum. 3. The input force is between the output force and the fulcrum in a ____________________ lever 4. The ______________ and _____________ provide a mechanical advantage greater than one. E. An _______________________ or ramp allows an object to be lifted over a greater distance using less force. 1. A ______________ is a moving inclined plane with one or two sloping surfaces. 2. ______________—inclined plane wrapped around a post 32 Motion, Forces, and Simple Machines Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc. Meeting Individual Needs A. _____________ Assessment Assessment 34 Motion, Forces, and Simple Machines Name Date Chapter Review Class Motion, Forces, and Simple Machines Assessment Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc. Part A. Vocabulary Review Directions: Write the term that matches each description below on the spaces provided. The heavily-boxed letters will spell something for which Isaac Newton is famous. 1. 2. 3. 4. 5. rate at which speed or direction changes measures the quantity of matter ______ = force × distance total distance divided by time speed of an object and its direction of motion 6. a push or pull 7. an inclined plane 8. force that resists motion between objects in contact 9. speed of an object at any instant in time 10. the number of times your force is multiplied 11. force that produces an acceleration 12. tendency to resist a change in motion 13. the boxed letters spell: Motion, Forces, and Simple Machines 35 Name Date Class Chapter Review (continued) Part B. Concept Review Directions: Fill in the blanks with the correct terms. 1. A machine that uses only one movement is a(n) ______________________________. 2. An object is accelerating if its ______________________________ or ______________________________ changes. 3. In a machine, the effort force you apply is used to overcome a ______________________________ force. 4. The speed of an object and its direction of motion are its ______________________________. 5. The speed of an object at any instant in time is its ______________________________ speed. 6. The less mass a moving object has, the _____________________________ it is to stop it. 7. Force pairs act on ______________________________ object(s). 8. A spring scale is used to measure ______________________________. 9. Machines can change the size of the force you apply, and/or change the ______________________________ of the force. Assessment 11. The smoother a surface is, the ______________________________ the force of friction. 12. According to Newton’s second law, an object acted on by a net force will accelerate in the direction of ______________________________. 13. If a person pushes on a wall with a force of 35 N, the force acting on the person is ______________________________. 14. To do work, a(n) ______________________________ must be applied and the object must move. 15. A ball dropped from a height of 125 m takes 5 s to hit the ground and is traveling at the rate of 50 m/s when it hits. a. The average speed of the ball in meters per second is ______________________________. b. The ball’s acceleration is ______________________________. c. After 3 seconds, the ball travels at a rate of ______________________________. d. After 4 seconds, the ball has traveled a distance of ______________________________. 36 Motion, Forces, and Simple Machines Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc. 10. Friction always ______________________________ an object. Name Date Chapter Test Class Motion, Forces, and Simple Machines I. Testing Concepts Directions: In the blank at the left, write the letter of the term that best completes each statement. 1. It would probably be easiest to ride a bicycle across ______. a. a sidewalk b. the grass c. sand d. gravel 2. The force that always acts opposite to the direction of the motion of an object is called ______. a. gravity b. inertia c. friction d. none of these 3. According to Newton’s third law, forces always occur in ______ pairs. a. equal but opposite c. unequal but complementary b. unequal but opposite d. equal but complementary 4. Newton first described gravity while watching ______. a. smoke rise b. a car accelerate c. someone walking d. an apple falling 5. You would NOT use ______ to find the acceleration of an object. a. time b. initial speed c. final speed d. weight 6. Newton’s ______ law of motion explains why you may lean sideways in a car if the driver turns a corner too quickly. a. primary b. first c. second d. third d. Velocity 8. To calculate an average speed, you would use ______. a. weight and time c. acceleration b. weight and distance d. distance and time Assessment Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc. 7. ______ is the speed of an object and its direction of motion. a. Friction b. Mass c. Gravity 9. ______ is used to describe an object slowing down because of decreasing speed. a. Acceleration c. Negative acceleration b. Average speed d. Inertia 10. A bottle opener is a(n) ______. a. first-class lever b. second-class lever c. third-class lever d. inclined plane 11. An object that has a ______ will accelerate in the direction of the force. a. normal force b. net force c. frictional force d. speed 12. ______ is the rate at which an object covers a given distance. a. Acceleration b. Speed c. Force d. Motion 13. ______ is NOT a force. a. Gravity b. Mass d. all of these c. Friction 14. A 1-cm screw with a 4-cm thread would have a mechanical advantage of ______. a. one b. two c. three d. four 15. Stepping from a wagon and watching the wagon move away from you is an example of Newton’s ______ law. a. first b. second c. third d. gravitational Motion, Forces, and Simple Machines 37 Name Date Class Chapter Test (continued) Directions: Identify each statement as true or false. Rewrite false statements to make them correct. 16. Acceleration is a rate that can describe how speed or direction is changing. 17. A compound machine is a combination of simple machines. 18. A combination of pulleys increases the effort force, so the mechanical advantage is greater than one. 19. Average speed does not include the time a car sits at red lights on the way home. 20. There is usually more friction on a smoother surface. Directions: If the statement or term identifies a force, list its number under Force. If it does not identify a force, list its number under Not a force. Not a force Assessment 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. the time it takes to make a trip the mass of a person on a scale the acceleration of a car turning a corner friction speed color taste the weight of a person standing still gravity pushing your friend toward the door 38 Motion, Forces, and Simple Machines Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc. Force Name Date Class Chapter Test (continued) II. Understanding Concepts Skill: Making and Using Tables Directions: Complete the table below by calculating the missing values. Object Initial speed A 0 m/s B Final speed Acceleration 4s 2 m/s 0 m/s 2s -4 m/s 10 m/s 2s 1. 2. 0 m/s C Time 2 2 3. 4. Use the information in the table above to answer the following questions. a. Which object has the greatest acceleration? b. Which object has negative acceleration? Assessment Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc. Skill: Concept Mapping Directions: Complete the following concept map that describes what happens when a cue ball is struck by the cue and then collides with the 8-ball. cue strikes cue ball cue ball accelerates cue ball strikes 8-ball cue ball 5. ____________ cue ball rebounds 8-ball moves opposite 6. ____________ 7. ____________ in same direction Motion, Forces, and Simple Machines 39 Name Date Class Chapter Test (continued) Skill: Designing an Experiment 8. How could you use a board and different materials found in the classroom to show the effect of friction on a rolling marble? III. Applying Concepts Directions: Do the following calculations. Show your work on the lines provided. 1. What is the average speed of a car traveling 210 km in 3 h? 2. Calculate the distance an object travels if its speed is 60km/h and it travels for 6 h. 3. Calculate the mass of an object with a force of 20 N and an acceleration of 2 m/s2. Assessment 5. Calculate the work of a weight lifter lifting a 400-N weight a distance of 2 m. IV. Writing Skills Directions: Answer the following questions using complete sentences. 1. According to Newton’s first law, if an arrow is shot in an open field, it should keep moving. Explain why the arrow eventually stops. 2. Explain what inertia means. 40 Motion, Forces, and Simple Machines Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc. 4. Calculate the acceleration of an object that starts at rest and accelerates smoothly to 20 m/s in 5 s. Transparency Activities Transparency Activities Motion, Forces, and Simple Machines 41 Name 1 Date Section Focus Transparency Activity Class It Must Be Math Calvin is right; calculating how fast you’re going is math. Whether Calvin does it himself or a speedometer does it for him, a calculation has to be made in order to find his speed. CALVIN AND HOBBES © Watterson. Reprinted with permission of UNIVERSAL PRESS SYNDICATE. All rights reserved. 2. Which method is best for measuring speed at a specific point on the hill? Which method is best for comparing how quickly two different sleds go down the hill? 3. Describe how the motion of the sled changes when it gets to the bottom of the hill. Transparency Activities 42 Motion, Forces, and Simple Machines Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc. 1. What two ways does the cartoon mention for measuring speed? Name 2 Date Section Focus Transparency Activity Class Bird’s Eye View 1. How will the skydivers’ motion change when their parachutes open? Transparency Activities Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc. Skydiving is a sport that many people enjoy. Experienced jumpers enjoy the feeling of free-fall before opening their parachutes. Working together, a team of skydivers can link arms to make formations like the one you see. 2. Does their motion continue to change after their parachutes open? Explain. 3. Would a heavier person fall more quickly than a lighter person? Give a reason for your answer. Motion, Forces, and Simple Machines 43 Name 3 Date Section Focus Transparency Activity Class Movin’ On 1. What do you see that helps the man move the boxes? 2. Where do you see wheels in this photograph? Transparency Activities 3. If you had to load this truck with heavy boxes, what tools would you want on hand? 44 Motion, Forces, and Simple Machines Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc. Moving is pretty hard work, but there are things that can help make it easier. As you look at this picture, try to imagine what it would be like if the man had only his bare hands to move the boxes. Name Teaching Transparency Activity Class Newton’s Laws of Motion Transparency Activities Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc. 2 Date Motion, Forces, and Simple Machines 45 Name Teaching Transparency Activity Date Class (continued) 1. If an object is accelerating, what can you infer about the forces acting on it? 2. What force set the ball in the top picture in motion? What force is slowing it down? 3. If the same force is applied to the refrigerator and the shopping cart, which will experience greater acceleration? Why? 4. Which law of motion do the action and reaction arrows illustrate? 6. In the photo of the swimmer, you can see the action and reaction arrows are the same size. Why don’t these forces cancel one another out? Transparency Activities 46 Motion, Forces, and Simple Machines Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc. 5. When you walk, what is pushing against your foot? Name Date Assessment Transparency Activity Class Motion, Forces, and Simple Machines 1. Newton’s third law says that forces act in opposing pairs. According to this information, what is the direction of the force the railroad tracks exert on the train? A1 B2 C3 D4 2. Which arrow indicates the force of friction? F1 G2 H3 J4 Transparency Activities Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc. Directions: Carefully review the diagram and answer the following questions. 3. If the forces indicated by arrows 2 and 4 are the same size, which of the following could describe the train’s motion? A Speeding up before reaching a hill B Slowing down as it approaches a downward slope C Running along a straight track at a constant speed D Applying the brakes slightly Motion, Forces, and Simple Machines 47 Teacher Support and Planning Teacher Support and Planning Content Outline for Teaching. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . T2 Spanish Resources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . T5 Teacher Guide and Answers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . T9 Motion, Forces, and Simple Machines T1 Section 1 Motion, Forces, and Simple Machines Motion A. Speed involves distance and time. Underlined words and phrases are to be filled in by students on the Note-taking Worksheet. 1. Average speed—calculated as total distance traveled divided by travel time 2. Instantaneous speed—an object’s speed at a particular moment 3. When instantaneous speed does not change, an object is moving at constant speed; average speed and instantaneous speed are the same in this situation. 4. Distance can be calculated if an object is moving at constant speed over a particular time period; total distance traveled equals average speed times time. B. Speed and direction of motion is velocity. C. Acceleration is the change in velocity divided by the time needed for the change to occur. 1. Acceleration can be calculated using a formula: acceleration equals change in speed divided by time. 2. Acceleration can be shown on a speed-time graph. DISCUSSION QUESTION: What two variables are involved in velocity? speed and direction of motion Section 2 Newton’s Laws of Motion A. Force—a push or a pull 1. When a force acts on an object, it changes the object’s acceleration. 2. Two or more forces that cancel each other out are balanced forces. 3. Two or more forces that do not cancel each other out are unbalanced forces. 4. The combination of all forces acting on an object is the net force. B. Newton’s laws of motion—explain how forces cause motion 1. Newton’s first law—a moving object moves in a straight line with constant speed unless a force acts on it. a. Friction—a force that resists movement between two surfaces in contact b. An object’s tendency to resist a change in motion is inertia; the more mass an object has, the greater its inertia. T2 Motion, Forces, and Simple Machines Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc. Teacher Support & Planning Content Outline for Teaching 2. Newton’s second law—if an object is acted upon by a net force, the change in velocity will be in the direction of the net force; acceleration can be calculated as acceleration equals net force divided by mass. 3. Newton’s third law—forces always occur in equal but opposite pairs; the equal and opposite forces act on different objects, so they are not balanced forces. DISCUSSION QUESTION: How are mass and inertia related? The greater an object’s mass, the greater its inertia. Section 3 Work and Simple Machines A. Work 1. Occurs when a force causes an object to move in the same direction that the force is applied 2. Calculated as work equals force times distance B. A simple machine uses only one movement; a compound machine is a combination of simple machines. 1. Mechanical advantage is the number of times force is multiplied; calculated as mechanical Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc. advantage equals output force divided by input force. 2. An ideal machine would experience no friction, so work in would equal work out. 3. Real machines experience friction, so work out is always less than work in. C. Pulley—an object with a groove, like a wheel, with a rope or chain running through the groove; changes the direction of the input force D. A lever is a rod or plank that pivots about a fixed point called the fulcrum. 1. The fulcrum is between the input force and the output force in a first-class lever. 2. In a second-class lever, the output force is between the input force and the fulcrum. 3. The input force is between the output force and the fulcrum in a third-class lever 4. The wheel and axle provide a mechanical advantage greater than one. E. An inclined plane or ramp allows an object to be lifted over a greater distance using less force. 1. A wedge is a moving inclined plane with one or two sloping surfaces. 2. Screw—inclined plane wrapped around a post DISCUSSION QUESTION: What is mechanical advantage? the number of times force is multiplied by a machine Motion, Forces, and Simple Machines T3 Teacher Support & Planning Content Outline for Teaching (continued) Movimiento, fuerzas y máquinas simples El movimiento Lo que aprenderás ■ ■ ■ A definir velocidad y aceleración. A relacionar la aceleración con el cambio de velocidad. A calcular distancia, velocidad y aceleración. Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc. Vocabulario average speed / velocidad media: tasa de movimiento que se calcula dividiendo la distancia recorrida por la cantidad de tiempo que se tarda en recorrer esa distancia. velocity / velocidad: rapidez de un cuerpo y su dirección de movimiento; cambia cuando cambia la rapidez, cuando cambia la dirección del movimiento o cuando las dos cambian. instantaneous speed / velocidad instantánea: rapidez de un objeto en cualquier momento dado. acceleration / aceleración: cambio en velocidad dividido por la cantidad de tiempo que se necesita para que ocurra el cambio; se presenta cuando un cuerpo acelera, decelera o cambia de dirección. Por qué es importante El movimiento puede describirse usando la distancia, el tiempo, la velocidad y la aceleración. Las leyes del movimiento de Newton Lo que aprenderás ■ ■ ■ A describir la forma en que las fuerzas afectan al movimiento. A calcular la aceleración usando la segunda ley del movimiento de Newton. A explicar la tercera ley del movimiento de Newton. Vocabulario force / fuerza: un empuje o un jalón; el newton es la unidad SI. Newton’s laws of motion / leyes del movimiento de Newton: conjunto de principios que explica el movimiento de los objetos. friction / fricción: fuerza resistente al movimiento entre dos superficies que se tocan y que siempre actúa opuesta a la dirección del movimiento. inertia / inercia: tendencia a resistir un cambio en movimiento. Por qué es importante Las leyes de Newton explican movimientos tan simples como caminar y tan complicados como el lanzamiento de un cohete. Trabajo y máquinas simples Lo que aprenderás ■ ■ ■ A definir trabajo. A distinguir los diferentes tipos de máquinas simples. A explicar cómo las máquinas facilitan el trabajo. Vocabulario work / trabajo: se lleva a cabo cuando una fuerza aplicada causa el movimiento de un cuerpo en la dirección de la fuerza. simple machine / máquina simple: dispositivo que facilita el trabajo con un movimiento solamente; puede cambiar el tamaño o la dirección de una fuerza; entre este tipo de máquina se incluyen la cuña, el tornillo, la palanca, la rueda y eje, la polea y el plano inclinado. compound machine / máquina compuesta: combinación de dos o más máquinas simples. mechanical advantage / ventaja mecánica: número de veces que una máquina multiplica la fuerza de esfuerzo que se le aplica. pulley / polea: máquina simple compuesta de una rueda acanalada con una cuerda, cadena o cable que corre a lo largo de una ranura; una polea cambia la dirección de la fuerza de esfuerzo y puede ser fija o movible. lever / palanca: máquina simple hecha de una barra libre para girar sobre un punto fijo. Movimiento, fuerzas y máquinas simples T5 Teacher Support & Planning Spanish Resources inclined plane / plano inclinado: máquina simple que consta de una superficie inclinada, como una rampa, que reduce la cantidad de fuerza que se necesita para levantar algo, al aumentar la distancia sobre la cual se aplica la fuerza. Por qué es importante Las máquinas facilitan el trabajo. Movimiento ¿Qué sucede cuando dejas rodar una pelota pequeña por una rampa? La pelota acelera al bajar la rampa, luego rueda por el piso y finalmente se detiene. Sabes que a medida que baja por la rampa, la gravedad actúa para acelerar la pelota. Piensa en las fuerzas que están actuando sobre la pelota al rodar sobre el piso. ¿Actúa una fuerza neta sobre la pelota? ¿De qué manera describirías el movimiento de la pelota? Preguntas del mundo real ¿Cómo se mueve la pelota cuando las fuerzas que actúan sobre ella están equilibradas y cuando no están equilibradas? Materiales pelota pequeña o canica metro o cinta métrica cronómetro papel para graficar Metas ■ Demostrar el movimiento de una pelota sobre la que actúan fuerzas equilibradas y desequilibradas. ■ Graficar la posición de la pelota con relación al tiempo. Medidas de seguridad Procedimiento 1. Coloca la pelota sobre el piso o una superficie plana y lisa. 2. Rueda la pelota por el piso empujándo la suavemente. T6 Movimiento, fuerzas y máquinas simples 3. Anota datos Cuando la pelota ya ruede sola haz que un alumno anote el tiempo y que otros anoten la distancia a intervalos de 1 s durante 5 ó 10 s. 4. Escribe todo lo que observes sobre el movimiento de la pelota. 5. Calcula la distancia que la pelota recorrió cada segundo. 6. Has un gráfico de la distancia que la pelota viajó versus el tiempo. Dibuja la distancia recorrida en el eje de y vertical y el tiempo en el eje de horizontal. 7. Escoge tres intervalos de un segundo. Calcula la velocidad de la pelota en cada uno de esos intervalos. Concluye y aplica 1. Describe cómo cambió la velocidad de la pelota a medida que rodaba por el piso. 2. Describe las fuerzas que actuaron sobre la pelota antes de empujarla, cuando estaba en reposo. Infiere si las fuerzas que actuaron sobre ella eran equilibradas o desequilibradas. 3. Describe las fuerzas actuando sobre la pelota a medida que rodaba por el piso. Infiere si las fuerzas que actuaron sobre ella eran equilibradas o desequilibradas. Comunica tus datos Compara tus gráficos con los de otros estudiantes de tu clase. Usa Internet Métodos de viaje Preguntas del mundo real ¿Cuánto tiempo te toma llegar al otro lado de la ciudad? ¿Cuánto tiempo toma llegar al otro lado del país? ¿Si estuvieras planeando un viaje de la ciudad de Nueva York a Los Ángeles, ¿cuánto tiempo se necesitaría? ¿Cómo cambiaría tu viaje si volaras? Cuando planeas un viaje de vacaciones, es útil estimar antes el tiempo de viaje. El tiempo de viaje depende del vehículo que usas, qué tan rápido viajas, la ruta Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc. Teacher Support & Planning Spanish Resources (continued) que tomes y hasta el terreno. Por ejemplo, manejar sobre montañas escabrosas puede llevar más tiempo que manejar por regiones agrícolas planas. Con esta información, puedes planear tu viaje de tal manera que llegues a tiempo a tu destino final. Formula una hipótesis sobre cuál es la forma más rápida de viajar. Metas Investigar tiempos de viaje. ■ Comparar tiempos de viaje en diferentes medios de transporte. ■ Evaluar la manera más rápida de viajar entre dos puntos. ■ Diseñar una tabla para mostrar tus hallazgos y comunicarlos a otros alumnos. ■ Fuente de datos Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc. Visita red.msscience.com/ internet_lab para más información sobre tiempos de viaje, medios de transporte, distancias entre lugares y datos de otros estudiantes. Diseña un plan 1. Escoge un punto inicial y un destino final. 2. Identifica las rutas que se usan comúnmente entre esas dos localidades. 3. Estudia los medios comunes de viajar entre esas dos localidades. 4. Investiga cómo estimar el tiempo de viaje. ¿Qué factores pueden hacer que tu viaje dure más o menos tiempo? Sigue tu plan 1. Asegúrate de que tu maestro(a) apruebe tu plan antes de comenzar. 2. Calcula el tiempo de viaje y la distancia entre tus dos localidades usando diferentes medios de transporte. Analiza tus datos 1. Analiza los datos que anotaste en tu Diario de ciencias para determinar el método más rápido de viajar. ¿Qué es mejor, manejar o volar? ¿Investigaste otro método de viaje? 2. Calcula la velocidad promedio para los medios de transporte que investigaste. ¿Cuál es el más rápido? ¿Cuál es el más lento? 3. Haz una tabla que compare el tiempo de viaje, la rapidez promedio y las distancias de los diferentes métodos de viaje. ¿Cuál es el método más rápido? ¿Es este siempre el más conveniente? ¿Qué factores aumentan el tiempo de viaje? 4. Comparte tus datos poniéndolos en el sitio Web de Glencoe Science. Concluye y aplica 1. Compara tus hallazgos con los de tus compañeros y con los datos publicados en el sitio Web de Glencoe Science. ¿Cuál fue la mayor distancia investigada? ¿La menor? 2. ¿Qué factores pueden afectar el tiempo de viaje de cada medio? ¿Cómo variaría tu tiempo de viaje si no hubieras tenido un vuelo directo? 3. Infiere cómo el promedio de velocidad de un vuelo cambiaría si en el tiempo total de viaje incluyeras la ida y el regreso al aeropuerto y los tiempos de espera. Comunica tus datos Halla este laboratorio usando el enlace red.msscience.com/internet_lab. Publica tus datos en la tabla provista. Combina tus datos con los de otros estudiantes y haz un cuaderno de viajes que estime el tiempo de viaje para varias localidades alrededor del mundo. Guía de estudio Sección 1 El movimiento 1. La velocidad promedio es la distancia recorrida dividida por el tiempo: s d/t 2. Un objeto está acelerando cuando su velocidad y/o dirección de movimiento cambia. 3. La aceleración puede calcularse al dividir el cambio de velocidad por el tiempo. Sección 2 Las leyes del movimiento de Newton 1. Inercia es una medida de la dificultad para alterar el movimiento de un cuerpo. Movimiento, fuerzas y máquinas simples T7 Teacher Support & Planning Spanish Resources (continued) 2. La primera ley de Newton establece que un cuerpo permanecerá en reposo o moviéndose con velocidad constante si no actúa ninguna fuerza sobre él. 3. La segunda ley de Newton describe la manera en que las fuerzas desequilibradas o las fuerzas netas actúan sobre un cuerpo. El cuerpo acelerará de acuerdo con Fnet = ma. 4. La tercera ley de Newton establece que las fuerzas actúan en pares iguales pero opuestos. Sección 3 Trabajo y máquinas simples 1. Se hace trabajo cuando una fuerza hace que un cuerpo se mueva en la dirección de la fuerza. El trabajo es igual a la fuerza aplicada multiplicada por la distancia sobre la que se aplica la fuerza. 2. Una máquina es un instrumento que hace más fácil el trabajo. Una máquina simple facilita el trabajo con un movimiento. Una máquina puede aumentar la fuerza, aumentar la distancia o cambiar la dirección de la fuerza aplicada. ¿Cómo facilita el trabajo esta palanca? 3. Ventaja mecánica es la fuerza de resistencia dividida por la fuerza de esfuerzo. 4. Los seis tipos de máquinas simples son: plano inclinado, cuña, tornillo, palanca, rueda y eje, y polea. Una máquina compuesta está hecha de máquinas simples. T8 Movimiento, fuerzas y máquinas simples Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc. Teacher Support & Planning Spanish Resources (continued) Hands-On Activities MiniLAB: Try at Home (page 3) 1. Answers will vary. 2. Answers will vary. 3. Answers will vary. MiniLAB: (page 4) 1. Students will observe that it is nearly impossible to prevent the sticks from being pulled together. 2. The more times the rope is wrapped around the sticks, the harder it is to keep the sticks from being pulled together. Lab (page 5) Lab Preview 1. flat surface 2. for at least 5 s to 10 s Conclude and Apply 1. The ball slows down and comes to a stop. 2. Gravity and static friction; because the ball’s motion did not change, no unbalanced force was acting on it. 3. Gravity and rolling friction; friction was the unbalanced force that caused the motion of the ball to change. Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc. Lab: Use the Internet (page 7) Analyze Your Data 1. Answers will be subjective and based on the students’ individual research. 2. Remind students that speed is calculated by dividing distance traveled by amount of time for the trip. 3. Students might conclude that the fastest method might not always be the most convenient. Factors such as flight schedules may influence their decisions. Conclude and Apply 1. Answers will vary based on each student’s individual research. 2. Weather conditions and time of day can affect travel times. Layovers can significantly add to travel time. 3. Average speed would decrease, as the time spent traveling to and from airports as well as waiting time can be significant. Questions and Conclusions 1. Students should find that the speeds are similar. 2. If the gutter is level, there should not be any apparent difference in speed. 3. Answers will vary. It is important to find out that position in the gutter is not a factor in regard to speed. 4. Students should find the results are the same no matter what the angle. 5. Objects of different mass fall at the same rate of speed. 6. Answers may vary but should include that the friction of the ramp will slow the marbles more than the friction of the air will. Laboratory Activity 2 (page 13) Data and Observations Answers will vary depending on the accuracy of student measurements. Questions and Conclusions 1. the hand pulling on the brick 2. The force needed to start the brick is greater than the force needed to keep the brick in motion. 3. The greater the mass of the brick, the greater the force needed to keep the brick in motion. 4. The greater the mass of a body, the greater the force needed to start a body in motion. 5. friction 6. The person inside the bus is moving with the speed of the bus. When the bus stops, the person will continue to move forward because of inertia. Meeting Individual Needs Directed Reading for Content Mastery (page 17) Overview (page 17) 1. 8 km/h 2. Laboratory Activity 1 (page 9) Data and Observations Tables 1 and 2 should show most or all marks in the last column, indicating both marbles fell at the same speed. Motion, Forces, and Simple Machines T9 Teacher Support & Planning Teacher Guide & Answers 3. action force 4. The box will collapse. 5. They increase the distance over which the force is applied, so you don’t need as much force. Sections 1 and 2 (page 18) 1. 120 m + 90 m + 50 m + 70 m = 330 meters 2. 330 m ÷ 2 min = 165 meters per minute 3. speed 4. speed 5. acceleration 6. net force 7. accelerate 8. opposite Section 3 (page 19) 1 Lectura dirigida para Dominio del contenido (pág. 21) Sinopsis (pág. 21) 1. 8 km/h 2. 3 D P 2 S I M P L E S A 4 T I N P U T A E N C 5 L E V E R 1. Force must be applied to an object and that object must move in the direction of the applied force to perform work. 2. A simple machine is one that has only one part. 3. √ 4. An inclined plane allows you to lift a heavy load by using less force over greater distance. Key Terms (page 20) 1. force 2. motion 3. acceleration 4. velocity 5. joules 6. output force 7. average speed 8. friction 9. lever 10. net force T10 Motion, Forces, and Simple Machines 3. acción fuerza 4. La caja se hundirá. 5. Aumentan la distancia sobre la cual se aplica la fuerza, de modo que no necesitas tanta fuerza. Secciones 1 y 2 (pág. 22) 1. 120 m + 90 m + 50 m + 70 m = 330 metros 2. 330 m ÷ 2 min = 165 metros por minuto 3. rapidez 4. rapidez 5. aceleración 6. fuerza neta 7. acelera 8. opuesto Sección 3 (pág. 23) 1 2 D I 3 S L A N O R A D A I M P T A P L E A 4 E N N C C A T A I A 1. La fuerza se debe aplicar al cuerpo y ese cuerpo debe moverse para realizar trabajo. 2. Una máquina simple es aquella que sólo consta de una parte. 3. X 4. Un plano inclinado te permite levantar una carga pesada al usar menos fuerza a lo largo de una distancia mayor. Términos claves (pág. 24) 1. fuerza 2. movimiento 3. aceleración 4. velocidad Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc. Teacher Support & Planning Teacher Guide & Answers (continued) 5. 6. 7. 8. 9. 10. julios fuerza de salida rapidez promedio fricción palanca fuerza neta Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc. Reinforcement (page 25) Section 1 (page 25) 1. acceleration 2. speed at a given time 3. average speed 4. distance traveled 5. 25 cm/min 6. 5 cm/min2 7. 10 cm/min 8. 30 cm 9. 0 10. it accelerates 11. (0 cm/min – 25 cm/min)/2 min = 12.5 cm/min2 12. negative acceleration 13. 1 (12.5)(2)2 = 25 cm 2 Section 2 (page 26) 1. a. third law b. first law c. second law d. first law e. second law f. third law 2. 0 3. friction 4. a = Fnet/m a = (0.2 N)/(0.25 kg) = 0.8 m/s2 5. The yo-yo will not accelerate as quickly; the larger the mass, the smaller the acceleration for the same amount of force. 6. 0.001 N Section 3 (page 27) 1. no work 2. no work 3. work 4–5. The object does not move. The object does not move in the same direction as the force. 6. You must apply force to an object, and the object must move in the same direction as the force you apply. 7. Work is measured in joules, Students may give the formula, 1 J = 1 N • m 8. the number of times a force is multiplied 9. They depend on the position of the fulcrum and the effort force and resistance force. In a firstclass lever, the fulcrum is between the effort force and resistance force. In a second-class lever, the resistance force is in the middle. In a third-class lever, the effort force is in the middle. 10. It changes the direction of the force. Enrichment (page 28) Section 1 (page 28) 1–3. Answers may include billowing clothing, depicting two or more versions of the character in the same panel as, for instance, the character swings on a vine, or over several panels showing people frozen in the background as the character races past. Cartoon panels: Answers will vary. Panel 1 may present Car A behind Car B, in panel 2 they may be even, and in panel 3 Car A may be pulling ahead. Students may include long vertical motion lines to simulate speed. They may even change the shape of the car to show that one is “working harder” to pass the other. 4. The first, constant motion, represents the formula speed = d/t. The second, accelerating motion, represents the formula a = (final speed – initial speed)/t. Section 2 (page 29) 1. Newton’s second law of motion 2. The ball would continue moving in a straight line until another force, such as the bat or gravity, changed its direction. The force and acceleration both come from the same place—the point of impact on the bat. 3. Answers will vary. Section 3 (page 30) 1. 5:1 2. 2:1 3. 2:1 4. 1:1 5. Gear d has the lowest ratio. It would be the best gear for riding uphill. Note-taking Worksheet (page 31) Refer to Teacher Outline, student answers are underlined. Assessment Chapter Review (page 35) Part A. Vocabulary Review (page 35) 1. acceleration (2/1) 2. mass (5/2) 3. work (7/3) 4. average speed (3/1) 5. velocity (1/1) 6. force (4/2) 7. ramp (8/3) 8. friction (5/2) 9. instantaneous speed (1/1) 10. mechanical advantage (9/3) 11. net force (4/2) 12. inertia (4/2) 13. laws of motion (4/2) Motion, Forces, and Simple Machines T11 Teacher Support & Planning Teacher Guide & Answers (continued) Part B. Concept Review (page 36) 1. simple machine (8/3) 2. speed, direction (1/1) 3. resistance (9/3) 4. velocity (2/1) 5. instantaneous (1/1) 6. easier (5/2) 7. different (6/2) 8. mass (5/2) 9. direction (9/3) 10. slows (2/1) 11. smaller (4/2) 12. the force (5/2) 13. 35 N (4/2) 14. force (7/3) 15. a.125 m/5 s = 25 m/s (3/1) b. (50 m/s)/5 s = 10 m/s2 (3/1) c. (10 m/s2) ✕ 3 s = 30 m/s (3/1) d. 1/2(10 m/s2)(4 s)2 = 80 m (3/1) Chapter Test (page 37) I. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. Testing Concepts (page 37) a (4/2) c (4/2) a (6/2) d (4/2) d (2/1) b (4/2) d (2/1) d (3/1) c (2/1) a (8/3) b (4/2) b (1/1) b (5/2) d (9/3) c (6/2) true (1, 2/1) true (9/3) true (8/3) false; Average speed does include the time a car sits at red lights on the way home. (3/1) 20. false; There is usually less friction on a smooth surface. (4/2) 21–30. Force—23, 24, 28, 29, and 30 Not a force—21, 22, 25, 26, and 27 (4/2) II. Understanding Concepts (page 39) 1. 8 m/s (3/1) 2. 8 m/s (3/1) 3. 5 m/s2 (3/1) 4. a. C (3/1) b. B (3/1) 5. slows down (4/2) 6. reaction or direction (4/2) 7. accelerates (4/2) T12 Motion, Forces, and Simple Machines 8. Answers will vary. One possible experiment would use the board as an inclined plane to consistently accelerate the marble. Materials at the base of the board could include concrete, linoleum, carpet, water, metal, wood, or sand. An accurate means of measuring time would also be necessary. (4/2) III. Applying Concepts (page 40) 1. s = d/t = 210 km/3 = 70 km/h (3/1) 2. d = s ✕ t = 60 km/h ✕ 6 h = 360 km (3/1) 3. F = m ✕ a; 20 = m ✕ 2; m = 20/2 = 10 kg (5/2) 4. a = (final speed – initial speed)/t = 20 – 0/5 = 4 m/s2 (5/2) 5. W = F ✕ d = 400 N ✕ 2 m = 800 N m = 800 joules or 800 J (7/3) IV. Writing Skills (page 40) 1. Gravity acts on the arrow, causing it to fall. Students may also know that air friction slows the arrow. (4/2) 2. Inertia is a tendency to resist a change in motion. Students may know that inertia is the measure of an object’s ability to stay at rest or to keep in motion. (4/2) Section Focus Transparency 1 (page 42) It Must Be Math Transparency Teaching Tips Ask the students why it’s important to know your speed while driving a car. The speedometer display is connected to the transmission and computes speed relative to the turning rate of the driveshaft. Explain the practical elegance of being able to compute the movement of real objects using numbers. ■ Ask students to explain what Hobbes means in the second panel of the cartoon strip. ■ Provide the students the following data and ask them to find the final speed in miles per hour. The distance traveled was 450 feet; the time was ten seconds. Remind them that after finding feet/second, they will have to change it to miles/hour. Tell them that they will need to complete four steps to solve the problem. (450 ÷ 10 = 45; 45 ✕ 60 = 2,700; 2,700 ✕ 60 = 162,000; 162,000 ÷ 5280 = 30.68, or around 31 miles per hour.) Using metrics and a distance of 137 meters, the math is as follows: 137 ÷ 10=13.7 × 60 = 822; 822 × 60 = 49,320; 49,320 ÷ 1000 = 49.32, or around 49 kilometers per hour. Make this as fun and easy as possible. Content Background ■ Besides driving, measuring speed is important in all forms of transportation. It is also used in predicting weather, numerous athletic events, and in science. ■ In luge, a form of sledding, speeds greater than 120 km/h (75 mph) have been attained. ■ Speed equals distance traveled divided by time. ■ Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc. Teacher Support & Planning Teacher Guide & Answers (continued) Answers to Student Worksheet 1. The cartoon mentions a speedometer and dividing distance by time. 2. The speedometer is best for getting the speed at a specific instant. On the other hand, average speed (distance divided by time) tells you which sled descended the hill more quickly. 3. Friction and some air resistance stop the sled. Section Focus Transparency 2 (page 43) Bird’s Eye View Transparency Teaching Tips You may use this transparency to introduce gravity as a force. According to Newton’s law of gravitation, every object in the universe attracts every other object (the exact mechanics at the atomic level are not yet understood). Tell the students that the greater the mass of the attracting object, the more force is applied. Drop a small book and a ruler and have students observe. Ask them why they landed at the same time. (The Earth’s gravitational pull is constant, the same for both.) ■ Ask the students whether skydivers fall at everincreasing speeds or at a constant rate as they hurtle earthward. ■ Ask the students why body position affects rate of descent (surface area exposed to air resistance). Content Background ■ The gravitational attraction (force) between two bodies is proportional to the mass of each, varying inversely to the square of the distance between them. ■ On Earth, a falling object accelerates from a resting position to terminal velocity, which is the fastest free-fall velocity. A skydiver accelerates in the direction of the force, or toward Earth. Terminal velocity for a skydiver is around 193 meters per second. ■ Earth’s gravitational force keeps the Moon in orbit. This force is actually causing the Moon to fall, not toward the Earth but from the straight line it would travel if gravity were not at work. ■ The first verifiable parachute jump was successfully completed in 1797 by the Frenchman Andre-Jacques Garnerin. He jumped from a balloon 1,000 meters (almost 3,300 feet) over Paris. Answers to Student Worksheet 1. The skydivers fall with increasing speed, attracted by the gravitational pull of Earth. Opening the parachute slows the rate of descent and allows the skydivers to land safely. 2. Opening the parachute causes an acceleration, slowing the skydivers’ fall. If a skydiver changes direction during a fall, that is another acceleration. 3. They fall at the same rate because the gravitational pull of Earth is constant (the same for everyone). Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc. ■ Section Focus Transparency 3 (page 44) Movin’ On Transparency Teaching Tips You may use this transparency to introduce simple machines. Point out and briefly explain the six simple machines—lever, pulley, wheel and axle, inclined plane, screw, and wedge. ■ Ask the students to identify the simple machines at work in the transparency. (They are the inclined plane, lever, and wheel and axle; perhaps a pulley is used on the rear sliding door.) ■ Have the students identify other machines in their daily lives, such as bicycles, garage doors, skateboards, etc. ■ Content Background ■ ■ ■ ■ ■ The wedge was probably the earliest tool, edged rocks being used by prehistoric people to split bones. A lever-balance device was probably used in Egypt about 5000 B.C. The inclined plane may date to about the same time. The wheel has been dated to Sumeria, around 3500 B.C. The spoked wheel and axle date to Asia Minor, around 2000 B.C. In the third century B.C., Archimedes supposedly pulled a boat from the water using a compound pulley. The Greeks may have been the first to use the screw, using it to press clothes in the second century B.C. One hundred years later, the screw was being used to press oil and wine. Answers to Student Worksheet 1. The ramp and the dolly are helping the mover get the boxes out of the truck. 2. There are wheels on the truck and wheels on the dolly. 3. Answers will vary. Students will probably mention the ramp and dolly. Other possibilities include tools like hammers and screwdrivers for taking large items apart. Encourage discussion of tools that make work easier. Teaching Transparency (page 45) Newton’s Laws of Motion Section 2 Transparency Teaching Tips Use the transparency to introduce the concept that motion occurs in predictable ways. Tell students that in the 1600s, Isaac Newton developed three laws of motion that helped to describe and predict how everyday objects move. ■ Ask students to identify the forces at work in the transparency. Remember to identify opposing pairs of forces. For example, if students say the hockey stick pushed the ball, they should also indicate the ball exerted a force on the stick. ■ Motion, Forces, and Simple Machines T13 Teacher Support & Planning Teacher Guide & Answers (continued) Reteaching Suggestion Review with students the three laws of motion and describe how the pictures on the transparency illustrate these laws. Extensions Activity: In pairs, have students devise an activity that demonstrates one of the laws of motion. Students should conduct the activities for the class. Challenge: Have students cut pictures from a newspaper or magazine that show objects in motion. Ask pairs of students to diagram and explain the forces at work on the objects in two of the pictures. Answers To Student Worksheet 1. You can infer the forces are unbalanced. 2. a push from the hockey stick; friction with the ground 3. The shopping cart will accelerate more because it has less mass. 4. Newton’s third law of motion 5. the ground 6. The forces don’t cancel each other out because they do not act on the same object. In this case, one force acts on the wall, and the other acts on the swimmer. The swimmer accelerates because she is experiencing unbalanced forces. ■ Assessment Transparency (page 47) Motion, Forces, and Simple Machines Section 3 Answers 1. A. Students must realize that the railroad tracks exert a force opposite in direction to the force exerted by the train on the tracks. 2. G. To answer this question, students must remember that friction is the force that resists motion between two surfaces in contact; friction acts opposite to the direction of motion. As it is drawn, the train is moving forward, so the force of friction must be indicated by arrow 2. 3. C. Forces indicated by arrows 2 and 4 are pointing in opposite directions, so, if they are the same size, they are balanced. Balanced forces do not cause a change in an object’s motion. Choice A: No, accelerating the train is a change in motion. Choice B: No, decelerating the train is also a change in motion. Choice C: Yes, the train will keep constant motion on a straight track. Choice D: No, this is similar to decelerating. Test-Taking Tip Remind students to read each question carefully to be sure they understand what is being asked. T14 Motion, Forces, and Simple Machines Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc. Teacher Support & Planning Teacher Guide & Answers (continued)