# Chapters 12 and 13 Review Questions

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Chapters 12 and 13 Review Questions

1. The strength of the gravitational force between two objects depends on the objects'
A. masses and the distance between them B. weights and accelerations C. momentum and velocities D. masses and velocities

2. Joseph throws a baseball straight forward
2. Joseph throws a baseball straight forward. At the same time, Corey drops a baseball from the same height. Which of the following is TRUE? A. Joseph's baseball falls faster than Corey's. B. Corey's baseball falls faster than Joseph's. C. Both baseballs fall at the same rate. D. You cannot predict which baseball will fall faster.

3. A satellite in orbit A. is not affected by gravity B. is always falling toward Earth C. must have a speed less than 8000 m/s D. cannot fall more than 5 m

4. An astronaut in an orbiting spacecraft floats because
A. Earth's gravity is too weak to affect the spacecraft B. the spacecraft and the astronaut fall at the same rate C. there is no force of gravity in space D. the spacecraft has a low acceleration

5. Friction resists motion between
A. any two objects B. surfaces in contact C. fluids only D. objects in free fall

6. Which of the following would increase the friction between a table and the floor?
A. pushing the table faster B. pushing the table slower C. taking heavy objects off the table D. putting heavy objects on the table

7. As you push an object, the frictional force resisting your push
A. remains constant once the object is moving B. continues to increase even after the object is moving C. steadily decreases after the object begins to move D. no longer resists once the object begins to move

8. Air resistance increases with
A. increased speed and decreased surface area B. decreased speed and increased surface area C. increased speed and increased surface area D. decreased speed and decreased surface area

9. The work a force does on an object depends on the
A. height of the object above the ground B. the size of the force and the distance it acts over C. acceleration and the mass of the object D. the potential energy of the object

10. A classmate lifts a book 50 cm
10. A classmate lifts a book 50 cm. You lift the same book 150 cm using the same force. Compared to your classmate, you have done A. one third the work B. three times the work C. nine times the work D. the same amount of work

11. Work can be measured in units called
A. newtons B. meters per second C. joules D. kilograms

12. Sean pushes a cart 100 m. Which of the following statements is TRUE?
A. The cart does work on Sean. B. Sean does no work. C. Sean does work on the cart over the entire 100 m. D. Work is done only when Sean first begins to push.

13. When Roger kicks a football, the football gains mechanical energy because Roger
A. does work on the football B. does work on the ground C. has more energy than the football D. has less energy than the football

14. Yelena holds a 5 kg ball over her head at a height of 2 m
14. Yelena holds a 5 kg ball over her head at a height of 2 m. What is the gravitational potential energy (GPE) of the ball? The formula for GPE is GPE = mgh, where g = 9.8 m/s2. A. 5 J B. 9.8 J C. 10 J D. 98 J

15. Quentin has a mass of 50 kg. When he rides his scooter at a velocity of 3 m/s, what is his kinetic energy? The formula for kinetic energy (KE) is KE = 1/2mv2. A. 50 J B. 75 J C. 225 J D. 450 J

16. To find the mechanical energy of an object,
A. multiply its kinetic energy and potential energy B. add its kinetic energy and potential energy C. divide its kinetic energy by its potential energy D. divide its potential energy by its kinetic energy

17. Kara does work on a ball by kicking it
17. Kara does work on a ball by kicking it. The work Kara does on the ball A. increases Kara's energy B. increases the ball's energy C. decreases the ball's energy D. decreases the ball's mass and height

18. If you double the distance over which a force moves an object, then the work is multiplied by

19. If you push a large rock as hard as you possibly can, and the rock does not move,
A. you do not use any force or do any work on the rock B. you use force, but do not do any work on the rock C. you do work on the rock, but do not use force D. you use force and do work on the rock

20. When you do work on an object, you transfer
A. power B. velocity C. energy D. acceleration

21. Which of the following does work?
A. a book lying on a table B. a person holding a book over her head C. a person reading a page of a book D. a person pushing a book across a floor

22. Which of the following will increase the amount of work you do pushing a box?
A. increasing the velocity of the box B. increasing the distance you push the box C. decreasing the distance you push the box D. decreasing the force you apply to the box

23. The force that attracts two masses to each other is called
A. air resistance B. friction C. gravity D. pressure

24. A hollow plastic ball and a solid metal ball are dropped from the same height in a vacuum. With no air resistance, gravity is the only force acting on the balls. What do you predict will happen? A. The balls will fall at the same rate. B. The metal ball will fall faster. C. The plastic ball will fall faster. D. The larger ball will fall faster.

25. After a space shuttle is launched into orbit, gravity
A. gives it a speed greater than 11,000 m/s B. no longer affects the astronauts on board C. makes it impossible for it to stay in orbit for a long period of time D. continues to pull it toward the center of Earth

26. Maria is sliding a box across the floor
26. Maria is sliding a box across the floor. She feels the box resisting her push. The resistance is caused by A. pressure B. friction C. gravity D. motion

27. The strength of the gravitational force between objects depends on
A. mass and distance B. pressure and area C. mass and volume D. force and acceleration

28. Without air resistance, for example, in a vacuum, the rate of acceleration resulting from Earth's gravity A. depends on the surface area of the falling object B. is the same for all objects, whatever their mass C. depends on the density of the falling object D. decreases as objects get closer to Earth

29. An astronaut in orbit experiences microgravity because he or she
A. is too far from Earth to be affected by gravity B. is falling at the same rate as the spacecraft C. is traveling faster than the escape velocity D. is accelerating fast enough to overcome friction

30. As Eli rubs a piece of wood with sandpaper, the wood becomes warmer. This release of heat is due to A. air pressure B. air resistance C. friction D. gravity

30. As Eli rubs a piece of wood with sandpaper, the wood becomes warmer. This release of heat is due to A. air pressure B. air resistance C. friction D. gravity

31. The formula for calculating the force of gravity on a mass close to Earth's surface is F = mg. The g in this formula is A. the mass of the object in grams B. the speed of the object as it falls C. acceleration caused by Earth's gravity D. constant velocity caused by Earth's gravity

32. Alison dives 5 meters below the surface of a lake
32. Alison dives 5 meters below the surface of a lake. The pressure on her A. decreases because under water there is no air pressure B. is directed upward because some objects are buoyant in water C. is directed downward because air is less dense than water D. increases because of the weight of all the water above her

33. Before doing a gymnastics routine on a high bar, Alysha puts rosin, a sticky substance, on her hands. She does this in order to A. increase air pressure B. decrease air resistance C. decrease gravity D. increase friction