Chapter 2 Section 1

1. Chapter 2 Section 1 Gravity and Motion Review!

2. 1. What is Terminal Velocity? • The motion of a body when only the force of gravity is acting on the body. • The curved path of a thrown object near Earth’s surface. • The constant velocity of a falling object when the force of gravity is balanced by air resistance. • The force that opposes the motion of objects thrown in the air.

3. ANSWER TERMINAL VELOCITY IS… C. The constant velocity of a falling object when the force of gravity is balanced by air resistance.

4. 2. What is Free Fall? • The force that opposes the motion of objects thrown in the air. • The curved path of a thrown object near Earth’s surface. • A song by Tom Petty and the Heartbreakers • The motion of a body when only the force of gravity is acting on the body.

5. ANSWER FREE FALL is… d. The motion of a body when only the force of gravity is acting on the body.

6. 3. What is Projectile Motion? • The motion of a body when only the force of gravity is acting on the body. • The curved path of a thrown object near Earth’s surface. • The constant velocity of a falling object when the force of gravity is balanced by air resistance. • The force that opposes the motion of objects thrown in the air.

7. ANSWER PROJECTILE MOTION is… b. The curved path of a thrown object near Earth’s surface.

8. 4. What is Air Resistance? • The force that opposes the motion of objects thrown in the air. • The curved path of a thrown object near Earth’s surface. • A song by Tom Petty and the Heartbreakers • The motion of a body when only the force of gravity is acting on the body.

9. ANSWER AIR RESISTANCE is… a. The force that opposes the motion of objects thrown in the air.

10. 5. Which of the following is in projectile motion? • A feather falling in a vacuum • A cat leaping on a toy • A car driving up a hill • A book laying on a desk

11. ANSWER b. A cat leaping on a toy.

12. 6. How is the acceleration of falling objects affected by gravity? • Gravity is not the same for all falling objects. • Gravity prefers pulling larger objects over smaller objects. • Gravity is constant for all falling objects. • Gravity prefers pulling smaller objects over larger objects.

13. ANSWER c. Gravity is constant for all falling objects.

14. 7. If a baseball and a cannonball are dropped from the same height at the same time, and there is no air resistance, which ball will hit the ground first? • The cannonball lands first. • The baseball lands first. • The balls land at the same time. • The ball with the larger volume lands first.

15. ANSWER c. The balls land at the same time.

16. 8. A boy standing on a high cliff dives into the ocean below and strikes the water after 3 seconds. What is the boy’s velocity when he hits the water? (Hint: Gravity pulls all objects at a rate of 9.8 meters/second) • 29.4 m/s • 36.2 m/s • 18.6 m/s • 15 m/s

17. ANSWER a. 9.8 x 3 = 29.4 m/s

18. 9. What feature of an object does not affect air resistance? • Its size • Its chemical properties • Its shape • Its speed

19. ANSWER b. Its chemical properties

20. 10. When does an object reach its terminal velocity? • When the upward force of air resistance equals the downward force of gravity. • When the downward force of gravity is greater than the upward force of air resistance. • When the downward force of air resistance is equal to the upward force of gravity. • When the upward force of air resistance is greater than the downward force of gravity.

21. ANSWER a. When the upward force of air resistance equals the downward force of gravity.

22. 11. A rock at rest falls off a tall cliff and hits the valley below after 3.5 seconds. What is the rock’s velocity as it hits the ground? (Hint: Think about the rate of constant acceleration) • 13.3 m/s • 6.3 m/s • 34.3 m/s • 2.8 m/s

23. ANSWER c. 9.8 x 3.5 = 34.3 m/s

24. 12. Why do astronauts appear to be floating when they are in space? • They are actually in free fall with the shuttle around Earth. • It’s really good special effects. • They weigh more in space. • They are forced to eat bad food.

25. ANSWER a. They are actually in free fall with the shuttle around the Earth.

26. 13. Centripetal force is…. • An unbalanced force that causes objects to move in a circular path. • The curved path of a thrown object near Earth’s surface. • The path of one object around another in space. • Luke Skywalker’s special friend

27. Answer CENTRIPETAL FORCE is… a. An unbalanced force that causes objects to move in a circular path.

28. 14. Which statement best describes the word “orbit”? • The force that opposes motion of objects through air. • The path of one object around another in space. • The motion of a body when only the force of gravity is acting on the body. • It’s an amusement park ride.

29. Answer ORBIT is… b. The path of one object around another in space.

30. 15. We could say that when an object is in projectile motion it is…. • The force that opposes the motion of objects through the air • The constant velocity of a falling object when the force of gravity is balanced by air resistance. • The curved path of a thrown object near Earth’s surface.

31. Answer c. The curved path of a thrown object near Earth’s surface.

32. GOOD LUCK TOMORROW!! STUDY HARD!! A copy of this guide is available on Mr. C.’s website Frost.sd54.org/mrcscience