Physics Review Quiz Motion and Forces; Energy Jan. 2012

1. Newton’s First Law says that when forces are _____________, no acceleration occurs. a. equal b. constant c. balanced d. removed

2. According to Newton’s Second Law, acceleration is directly proportional to__________ and inversely proportional to _______________. a.speed; time b. distance; force c. force; time d. force; mass

3. A 3-kg mass is accelerated at a rate of 12 m/s 2. What amount of force caused the acceleration? a.0.25 N b. 4 N c. 9 N d. 15 N e. 36 N

4. Two equal masses are accelerated by forces of 2 N and 4 N. The second mass accelerates a.the same as the first, since all masses accelerate at the same rate b. twice as fast as the first, since it has twice the force applied c. four times as fast as the first, because 2 squared is 4

5. A baseball player strikes the ball with his bat. The force on the ball a. is equal to the force on the bat b. is smaller than the force on the bat c. is larger than the force on the bat

6. The momentum of a 5-kg mass moving at 3 m/s is a.1.67 m/s b. 15 kg·m/s c. 0.6 kg·m/s d. 0.6 m/s 2

7. The momentum of a 1-kg mass after accelerating from rest at 3 m/s 2 for 4 seconds is a.12 m/s b. 12 kg·m/s c kg·m/s 2 d. 12 N

8. It is impossible for a marshmallow to have as much momentum as a jumbo jet. a.true b. false

9. To change the momentum of an object, you must apply an impulse. Impulse is a.the product of force and distance b. the product of force and velocity c. the product of time and force d. the sum of force and distance

10. Impulse is equal to a.change in potential energy b. change in kinetic energy c. change in momentum d. both a and b

11. To change the momentum of an object from 10 kg·m/s to 14 kg·m/s, a force of 8 N must be applied for a. 140 seconds b. 2 seconds c. one-half second d. 80 seconds

12. A 75-kg figure skater gliding across the ice at 4 m/s comes to a complete stop after 20 seconds. The friction on his skates must have been a. 300 N b. 80 N c. 15 N d.1500 N

13. A billiard ball going 3 m/s collides with an identical ball at rest. The first ball comes to a complete stop after the collision. The second ball a.moves away at 3 m/s, but in the other direction from the direction the first ball was moving b. moves away at an angle, less than 3 m/s c. has the same velocity as the first ball had before the collision

14. An object is in equilibrium if it is a.in free fall b. moving at constant speed c.at rest with no net force acting on it d. supported by a normal force e. all the above

15. The property of resisting changes in motion in the absence of an outside force is called a.inertia b. constant velocity c. equilibrium d. negativism

16. The support force of a table on a book is also called the normal force because a. all tables have it b. all books have it c. its just ordinary d. it acts upward e. it acts perpendicular to the table

17. An arrow with a momentum of 0.75 kg·m/s hits a stationary target and sticks. Immediately after the arrow hits, the arrow and target a.have zero momentum b. have –0.75 kg·m/s momentum c. have 0.75 kg·m/s momentum d. there’s no way to tell

18. Two identical blobs of putty move towards each other at the same speed and stick together when they hit. Immediately after the collision, their combined momentum is a.zero b. the same as it was before c. twice the individual momentum d. both a and b

19. A 100 watt engine is used to pull a 10-kg load up to the roof of a 30 meter high building. How long did it take? a minutes b seconds c. 30,000 seconds d. 300 seconds

20. An object having 8,000 joules of potential energy falls out of a window. When it hits the sidewalk, its potential energy a.is still 8,000 joules b. is zero c. instantly changes to kinetic energy d. both b and c e. both a and c

21. A 2-kg mass with a 3 m/s velocity has a kinetic energy of a. 6 kg·m/s b. 6 joules c. 1.5 joules d. 9 joules e. 9 kg·m/s

22. Doing work on an object changes a. where it is b. how fast it’s moving c. its total energy d. its mass e. its value

23. Momentum is conserved in a. elastic collisions b. inelastic collisions c. all collisions d. small mason jars

24. Kinetic energy is conserved in a. inelastic collisions b. elastic collisions c. all collisions d. large mason jars

25. A man carries a 2-kg rock from a 10 meter high hill to a 20 meter high hill. The potential energy of the rock a. doubled b. quadrupled c. did not change d. changed to kinetic energy

26. How much work has to be done to stop a 10-kg object moving with a velocity of –10 m/s? a. 500 joules b. 100 newtons c. –100 newtons d. –100 joules e. –1,000 joules

Check your answers. Write the number correct on your paper and turn it in. 1.c7.b13.c 2.d8.b14.c 3.e9.c15.a 4.b10.c16.e 5.a11.c17.c 6.b12.c18.d

19.b 20.b 21.d 22.c 23.c 24.b 25. a

For 20 points extra credit in the quiz column, complete this problem for homework, showing all your work. Copy it now on a new sheet of paper.

26. How much work has to be done to stop a 10-kg object moving with a velocity of –10 m/s? Turn in your quiz and