Section 2: Newton s Laws of Motion (p. 145)

Transcription

1 Section 2: Newton s Laws of Motion (p. 145) 1. In 1686, published Principia, a work explaining laws to help people understand how forces relate to the of objects. Newton s First Law of Motion (p. 145) 2. What is Newton s first law? 3. An object in motion would keep moving forever if it never ran into another object or an unbalanced force. True or False? 4. is the unbalanced force that slows down sliding desks, rolling baseballs, and moving cars. 5. How does inertia explain why it would be so difficult to play softball with a bowling ball? 44 HOLT SCIENCE AND TECHNOLOGY

2 Newton s Second Law of Motion (p. 148) 6. What is Newton s second law of motion? CHAPTER 6 7. Look at the Environmental Science Connection. A small car with a small engine cannot accelerate as well as a large car with a large engine. True or False? 8. An object s acceleration decreases as the force on it increases. True or False? 9. Force equals times. 10. The watermelon in Figure 16 has more and than the apple, so the watermelon is harder to move than the apple. Review (p. 149) Now that you ve finished the first part of Section 2, review what you ve learned by answering the Review questions in your ScienceLog. Newton s Third Law of Motion (p. 150) 11. What is Newton s third law of motion? 12. The phrase equal and opposite means that the action force and the reaction force have the same but act in opposite. DIRECTED READING WORKSHEETS 45

3 13. What action and reaction forces are present when you are sitting on a chair? 14. In a force pair, the reaction and action forces affect the same object. True or False? 15. When a ball falls off a ledge, gravity pulls the ball toward Earth and also pulls Earth toward the ball. True or False? Momentum Is a Property of Moving Objects (p. 152) 16. Why does it take longer for a large truck to stop than it does for a compact car to stop, even though they are traveling at the same velocity and the same braking force is applied? 17. Momentum depends on the and of an object. 18. In Figure 19, during the collision, the momentum of the cue ball a. is added to the total momentum. b. is transferred to the billiard ball. c. is transferred to the table holding the balls up. d. stays with the cue ball. 19. The law of conservation of momentum states that any time two or more objects interact, they may exchange momentum, but the total amount of momentum stays the same. True or False? Review (p. 153) Now that you ve finished Section 2, review what you ve learned by answering the Review questions in your ScienceLog. 46 HOLT SCIENCE AND TECHNOLOGY

4 Section 2: Newton s Laws of Motion (p. 145) 1. In 1686, Sir Isaac Newton published Principia, a work explaining three laws to help people understand how forces relate to the motion of objects. Newton s First Law of Motion (p. 145) 2. What is Newton s first law? An object at rest remains at rest and an object in motion remains in motion at a constant speed and in a straight line unless acted on by an unbalanced force. 3. An object in motion would keep moving forever if it never ran into another object or an unbalanced force. True or False? 4. Friction is the unbalanced force that slows down sliding desks, rolling baseballs, and moving cars. 5. How does inertia explain why it would be so difficult to play softball with a bowling ball? The bowling ball has more mass than a softball, so it also has more inertia than a softball. Having lots of inertia would make it difficult to change the bowling ball s direction once it is moving. After the bowling ball is pitched toward you, it would be hard for you to bat it away with a bat. 44 HOLT SCIENCE AND TECHNOLOGY

5 Newton s Second Law of Motion (p. 148) 6. What is Newton s second law of motion? The acceleration of an object depends on the mass of the object and the amount of force applied. CHAPTER 6 7. Look at the Environmental Science Connection. A small car with a small engine cannot accelerate as well as a large car with a large engine. True or False? 8. An object s acceleration decreases as the force on it increases. True or False? 9. Force equals mass times acceleration. 10. The watermelon in Figure 16 has more mass and inertia than the apple, so the watermelon is harder to move than the apple. Review (p. 149) Now that you ve finished the first part of Section 2, review what you ve learned by answering the Review questions in your ScienceLog. Newton s Third Law of Motion (p. 150) 11. What is Newton s third law of motion? Whenever one object exerts a force on a second object, the second object exerts an equal and opposite force on the first. Or, all forces act in pairs. 12. The phrase equal and opposite means that the action force and the reaction force have the same size but act in opposite directions. DIRECTED READING WORKSHEETS 45

6 13. What action and reaction forces are present when you are sitting on a chair? The action force is your weight pushing down on the chair. The reaction force is the force exerted by the chair that pushes up on your body and is equal to your weight. 14. In a force pair, the reaction and action forces affect the same object. True or False? 15. When a ball falls off a ledge, gravity pulls the ball toward Earth and also pulls Earth toward the ball. True or False? Momentum Is a Property of Moving Objects (p. 152) 16. Why does it take longer for a large truck to stop than it does for a compact car to stop, even though they are traveling at the same velocity and the same braking force is applied? It takes the truck longer to stop because it has more momentum. 17. Momentum depends on the mass and velocity of an object. 18. In Figure 19, during the collision, the momentum of the cue ball a. is added to the total momentum. b. is transferred to the billiard ball. c. is transferred to the table holding the balls up. d. stays with the cue ball. 19. The law of conservation of momentum states that any time two or more objects interact, they may exchange momentum, but the total amount of momentum stays the same. True or False? Review (p. 153) Now that you ve finished Section 2, review what you ve learned by answering the Review questions in your ScienceLog. 46 HOLT SCIENCE AND TECHNOLOGY