sample test 2
Student: ___________________________________________________________________________
1. Which of the following is not an energy unit? 
 
A. N·m
B. Joule
C. calorie
D. watt
E. kWh
 
2. A brick slides across a horizontal rough surface and eventually comes to a stop. What happened to the kinetic energy of the brick? 
 
A. Nothing, it is still in the brick but is now called potential energy.
B. It was converted to other energy forms, mostly heat.
C. It was converted to a potential energy of friction.
D. It was simply destroyed in the process of stopping.
 
3. The power of an engine is a measure of 
 
A. its volume.
B. its ability to outperform a horse.
C. the rate at which it can perform work.
D. the total amount of work it can perform.
 
4.  Which has the greater kinetic energy — a 1-ton car moving at 30 m/s, or a half-ton car moving at 60 m/s?  
 
A.  The 1-ton car. 
B.  The half-ton car. 
C.  Both have the same kinetic energy. 
D.  Cannot determine this because the mass of the cars can't be found. 
 
5. A 20 N ball and a 40 N ball are dropped at the same time from a height of 10 meters. Air resistance is negligible. Which of the following statements is accurate? 
 
A. After 1 second has elapsed, both balls have the same kinetic energy since they have the same acceleration.
B. The heavy ball has a greater acceleration and falls faster.
C. The light ball has a greater speed since it can accelerate faster than the heavy ball.
D. Both balls hit the ground at the same time but gravity does more work on the heavy ball than on the light ball.
 
6. A block sits on a slight incline, held at rest by the frictional force between the block and the incline. Which of the following statements is true? 
 
A. The frictional force performs no work since there is no motion of the block.
B. The work by the frictional force is equal to the gravitational potential energy of the block.
C. The work done by the frictional force is negative since the force of friction opposes the direction that the block is being tugged by gravity.
D. The work done by gravity is entirely converted into heat because of the friction present.
E. None of these is true.
 
7. Initially, a blue automobile has twice the kinetic energy that a red automobile has. Both are braked to a stop; both have the same amount of braking force. The red auto will stop in ____________________ as the blue auto. 
 
A. half the distance
B. the same distance
C. twice the distance
D. four times the distance
E. one fourth the distance
 
8. Jim exerts a force of 500 N against a 100-kg desk that does not move. Virgil exerts a force of 400 N against a 60-kg desk that moves 2 m in the direction of the push. Mik exerts a force of 200 N against a 50-kg desk that moves 4 m in the direction of the push. The most work is done by 
 
A. Jim.
B. Virgil.
C. Mik.
D. Virgil and Mik, who do equal amounts of work.
 
9. An object with a kinetic energy of 50 J is stopped in a distance of 0.01 m. The average force that stops the object is 
 
A. 0.5 N.
B. 50 N.
C. 500 N.
D. 5,000 N.
E. 50,000 N.
 
10. For a 0.1-kg frog to jump to a height of 1.0 meter requires an energy of about 
 
A. 0.1 Joule.
B. 0.5 Joule.
C. 1.0 Joule.
D. 10 Joule.
 
11. A 3.0-kg cat runs to the left at 10 m/s and a 12-kg dog runs to the right at 4.0 m/s. The total kinetic energy is 
 
A. -54 Joule.
B. 0.
C. 162 Joule.
D. 246 Joule.
E. 270 Joule.
 
12. A child riding on a swing rises to a height 1.0 m above the lowest point. Another child of equal mass whose speed at the lowest point is twice as great will rise 
 
A. to the same height.
B. twice as high.
C. four times as high.
D. to a height which depends on the mass.
 
13. A box is moved 10 m across by a floor a force of 20 N acting along the direction of motion. The work done by the force is 
 
A. 2.0 J.
B. 20 J.
C. 30 J.
D. 100 J.
E. 200 J.
 
14. A box is pushed across a rough horizontal floor by a force acting parallel to the floor in the direction of motion. A force doing negative work on the body is 
 
A. gravity.
B. friction.
C. the applied force.
D. the normal reaction force of floor upward on body.
E. a fictitious force.
 
15. Which of the following is not a unit of power? 
 
A. watt
B. kilowatt
C. kilowatt-hour
D. joule/second
E. horsepower
 
16. A body is suspended from a spring hanging vertically. The body is then pulled downward so the spring stretches. Consider the change in the elastic potential energy (EPE) of the spring and the change in gravitational potential energy (GPE) as the body is pulled down. 
 
A. The EPE increases but the GPE is unchanged.
B. The GPE increases along with the EPE.
C. The GPE decreases while the EPE increases.
D. The GPE decreases but the EPE is unchanged.
E. Both the GPE and the EPE decrease.
 
17. A bullet of mass 0.010 kg and speed of 100 m/s is brought to rest in a wooden block after penetrating a distance of 0.10 m. The work done on the bullet by the block is 
 
A. 50 J.
B. -50 J.
C. 0.001 J.
D. -0.001 J.
E. zero
 
18. A force is applied to an object. The total energy of the object does not change. Which of the following is true? 
 
A. The force is applied perpendicular to the direction of motion.
B. The applied force is friction.
C. The force does work on the object.
D. There must be more than one force on the object.
 
19. When a baseball bat hits the ball, the impulse delivered to the ball is increased by 
 
A. "follow through" on the swing.
B. rapidly stopping the bat after impact.
C. letting the bat recoil upon impact.
D. impulse cannot be changed.
 
20. Suppose you are out on a frozen lake, where there is no friction. Which of the following would start you moving towards the shore? 
 
A. Shouting at someone on the shore.
B. Removing a shoe and throwing it towards the shore.
C. Removing a shoe and throwing it away from the shore.
D. None of these would work.
 
21. A gun is made of a super-low weight but strong material. The bullet for the gun is more massive than the gun itself. For such a gun 
 
A. recoil problems would be lessened.
B. the gun, if unsupported, would have a recoil velocity higher than the bullet velocity.
C. conservation of momentum is not satisfied.
D. the bullet would go faster with less powder.
 
22. The purpose of an air bag in an auto is to 
 
A. reduce your speed just before a collision.
B. decrease the force applied to you during a collision.
C. reduce the impulse on you during a collision.
D. make your momentum change occur over a shorter time during a collision.
 
23. A bowling ball, moving to the east at a speed of 1.4 m/s, collides head-on with a stationary beach ball of the same diameter but less than one twentieth the mass. After the collision, the beach ball moves with a speed of 1.6 m/s. Which of the following is then true? 
 
A. The bowling ball has a velocity of slightly under 1.4 m/s, to the east.
B. The beach ball has more momentum than the bowling ball.
C. The bowling ball recoils to the west with nearly the same speed as before the collision.
D. The bowling ball and the beach ball have the same momentum after the collision.
 
24. A ping-pong ball is dropped vertically, onto a stationary bowling ball resting on the floor. Which of the balls experiences the greater force as a result of the collision? 
 
A. Neither, both experience forces of the same size.
B. The ping-pong ball.
C. The bowling ball.
D. It's impossible to tell from this data.
 
25. Force F, acting for time T and over a distance D, gives impulse I. To get the same impulse using half the force, it would be necessary for the force to act 
 
A. over a distance 2D.
B. over a distance 4D.
C. over half the distance D.
D. for a time 2T.
E. for half the time T.
 
26. Two people sit face to face on chairs that are free to roll without friction. They push each other with a force of 50 N and move apart. Person A, whose mass (including the chair) is 80 kg, moves to the left at 2.5 m/s. Person B, whose mass (including the chair) is 50 kg, 
 
A. moves to the right at 2.5 m/s.
B. moves to the right at 4 m/s.
C. moves to the right at 3.16 m/s.
D. moves to the right at 10 m/s.
 
27. A 20-kg child runs at 4.0 m/s and jumps onto a shopping cart, which also has mass 20 kg. 
Assuming the child rides on the cart after the collision, the speed of the child and shopping cart,
just after the child jumps on, is 
 
A. zero.
B. 2.0 m/s.
C. 3.0 m/s.
D. 4.0 m/s.
 
28.  The average force required to accelerate a 0.20-kg ball from rest to 30 m/s in 0.001 s is  
 
A.  0.006 N 
B.  6,000 N. 
C.  30,000 N. 
D.  150,000 N. 
 
29. A box is pushed eastward across a rough horizontal floor by a force acting parallel to the floor. A force providing an impulse directed westward on the body is 
 
A. gravity.
B. friction.
C. the applied force.
D. normal reaction force of floor upward on body.
E. a fictitious force.
 
30. A 2 kg block, initially moving due east at 6 m/s, is acted upon by an impulse having magnitude 4 Ns and direction due west. The final velocity of the block is 
 
A. 8 m/s west.
B. 4 m/s west.
C. 4 m/s east.
D. 8 m/s east.
 
31. A car moving east collides with a truck moving north. The vehicles have the same speed but the truck has twice the mass of the car. If the vehicles stick together after the collision, what is the path followed by the vehicles after the collision?

 
A. A
B. B
C. C
D. D
E. E
 
32. If a single force acts on a moving object 
 
A. the momentum of the object must change.
B. the momentum of the object will change only if the force is in the same direction as the velocity of the object.
C. the momentum of the object can only change magnitude, not direction.
D. the momentum of the object can only change direction, not magnitude.
 
33. An isolated object is initially spinning at a constant speed. Then, although no external forces act upon it, its rotational speed increases. This must be due to 
 
A. an increase in the moment of inertia.
B. an increase in the mass.
C. an increase in the angular momentum.
D. a decrease in the moment of inertia.
E. impossible, angular momentum conservation is violated.
 
34. The bigger gears on the rear wheel of a multi-speed bike allow the rider to 
 
A. exert more force on the wheel.
B. exert more torque on the wheel.
C. increase the moment of inertia of the wheel.
D. decrease the moment of inertia of the wheel.
 
35. Using a longer handled wrench to loosen a tight nut allows you to 
 
A. exert more force on the nut.
B. increase the moment of inertia of the nut.
C. apply more torque to the nut.
D. pull harder on the wrench.
 
36. Because the rotational inertia is higher, it is hardest in springboard diving to perform a forward somersault in 
 
A. the straight position (no bending at knees or waist).
B. the pike position (bending at the waist but not the knees).
C. the tuck position (bending at both the waist and knees).
 
37. When an ice skater twirling on the point of a skate draws her arms in she ends up whirling faster. This is because 
 
A. rotational energy is conserved.
B. angular momentum is conserved.
C. linear momentum is conserved.
D. a net torque acts on the skater.
 
38. The armature of a motor is accelerated uniformly from rest to a rotational velocity of 1800 rev/min in 10 seconds. The rotational acceleration of the motor is 
 
A. 180 rad/s2.
B. 90 rad/s2.
C. 37.7 rad/s2.
D. 18.8 rad/s2.
E. zero.
 
39. Which of the following is an appropriate unit for describing rotational acceleration? 
 
A. m/s2.
B. rad/min.
C. rev/min.
D. rev/m/s.
E. rev/min2.
 
40. A body of rotational inertia 1.0 kg m2 is acted upon by a torque of 2.0 Nm. The angular acceleration of the body will be: 
 
A. 0.5 rad/s2.
B. 0.5 rev/s2.
C. 1.0 rad/s2.
D. 2.0 rad/s2.
E. 2.0 rev/s2.
 
41. A student plays on a see-saw with her father. The student has a weight of 250 N and is seated 2.4 m from the axis of rotation. Her father balances her when he is seated 0.8 m from the axis. The father's weight is: 
 
A. 250 N.
B. 500 N.
C. 667 N.
D. 725 N.
E. 750 N.
 
42. If the net force on a body is zero, the net torque on the body is 
 
A. always zero.
B. not necessarily zero.
C. certainly not zero.
 
43. If the net torque on a body is zero, the net force on the body is 
 
A. always zero.
B. not necessarily zero.
C. certainly not zero.

ANSWERS		SAMPLE TEST 2

1.	D					1. 	 1,000,000N		5,000Ns		
2.	B					2.	 34.16KJ		27.55m/s
3.	C					3.	-1.6Nmrad		50 rad
4.	B					4.	 Inelastic                    CR = 1/8
5.	D						
6.	A
7.	A
8.	D
9.	D
10.	C
11.	D
12.	C
13.	E
14.	B
15.	C
16.	C
17.	B
18.	A
19.	A
20.	C
21.	B
22.	B
23.	A
24.	A
25.	D
26.	B
27.	B
28.	B
29.	B
30.	C
31.	B
32.	A
33.	D
34.	B
35.	C
36.	A
37.	B
38.	D
39.	E
40.	D
41.	E
42.	B
43.	B

1.	During a  0.0050 second time period a rocket expels 1.000kg of gas at a velocity of 5000m/s.   Calculate the rocket’s average thrust.  Calculate the impulse received by the rocket. 

2.	A 90.0kg skier has 140KJ of total mechanical energy when he is at a height of 120m above the bottom of the hill.  Calculate the skier’s kinetic energy.  Calculate his speed.

3.	A ball with an initial angular velocity of 20.0 rads /s and a rotational inertia of 0.4kgmrolls uphill with an acceleration of -4.00 rad/s.   Calculate the net torque acting on the ball.  Calculate the angular displacement after 5.00 s.   

       

4.	A 2kg box is sliding east at 50m/s on a frictionless floor when it collides with a 4kg box sliding east at 10m/s.  After the collision, the 2 kg box is sliding east at 20m/s and the 4kg block is sliding east at 25m/s.  Calculate the coefficient of restitution.  What type of collision is this?