1. This and the following two questions concern the same physical situation.
A ball is thrown upward from the ground at an initial angle of 60A?° with respect to the horizontal and with an initial speed of 30 m/s. How high does the ball rise above the ground?
(a) 34.4 m
(b) 15.4 m
(c) 9.8 m
(d) 25.0 m
(e) 12.5 m
2. In the preceding question, what is the total time the ball is in the air before returning to ground level?
(a) 1.4 s
(b) 7.2 s
(c) 5.3 s
(d) 8.7 s
(e) 6.5 s
3. In the preceding question, suppose instead that the ball is initially thrown straight up with the same initial speed of 30 m/s. Compared to the preceding question, the total time the ball is in the air is now
(a) the same.
(b) less.
(c) greater.
4. Ball A is released from rest from the top of a tall building. Ball B is projected horizontally from the top of the same building with a non-zero speed. Which ball has the higher speed as they hit the ground?
(a) ball A
(b) ball B
(c) they have the same speed as they hit the ground
5. This and the following questions concern the same physical situation.
A 1200-kg car (which you may approximate as a point object) rounds a circular curve of radius R = 45 m. If the coefficient of static friction between the tires and the road is A?µs = 0.82, what is the maximum speed the car can have in the curve without the tires slipping?
(a) 25.2 m/s
(b) 11.8 m/s
(c) 15.8 m/s
(d) 19.0 m/s
(e) 30.6 m/s
6. Let your answer to the preceding problem be V. Suppose instead that the mass of the car is twice as large but that the radius of the curve is also twice as large. What is now the maximum speed the car can have in the curve without the tire slipping?
(a) V
(b) 1.414 V
(c) 2 V
7. This and the following question concern the same physical situation.
A block of mass 4.0 kg is sitting on a horizontal frictionless surface and is pulled with a rope that makes an angle of 30A?° with the horizontal, as shown in the drawing below. The tension in the rope is 25 N. What is the acceleration of the block along the surface?
(a) 5.41 m/s2
(b) 7.81 m/s2
(c) 2.24 m/s2
(d) 3.54 m/s2
(e) 8.42 m/s2
8. In the preceding question, let the weight of the block be denoted by W. How does the normal force FN compare with W?
(a) FN > W
(b) FN = W
(c) FN < W
9. A ball of mass M is suspended vertically from the end of a string. The other end of the string is attached to the ceiling of an elevator, as shown in the figure. The elevator is initially moving downward at constant speed. Just before reaching the bottom floor, the elevator slows down. As it is slowing down, the tension in the string will be
(a) greater than Mg.
(b) equal to Mg.
(c) less than Mg.
10. This and the following question concern the same physical situation.
Block A of mass 2 kg and block B of mass 4 kg are attached to each other by a string. The two blocks are sitting on a horizontal frictionless surface. Another string is attached to block B and the whole system is pulled to the right so that both blocks accelerate together, as shown in the figure. If the tension T is 15 N, as shown in the figure, what is the tension T1 in the string connecting the two blocks?
(a) 1 N
(b) 3 N
(c) 5 N
(d) 12 N
(e) 15 N
11. In the preceding question, suppose the order of the two blocks is reversed so that block A is in front and B is in back, with the same tension T = 15 N, as shown in the figure. Compared to the preceding problem, the tension T1 is now
(a) greater.
(b) less.
(c) the same.
12. This and the following question concern the same physical situation.
A block of mass M = 6 kg slides down an incline at constant velocity. The incline makes an angle of 40A?° with respect to the horizontal, as shown in the figure. What is the coefficient of kinetic friction between the block and the incline?
(a) 0.92
(b) 0.84
(c) 0.76
(d) 0.65
(e) 0.24
13. In the preceding problem, suppose the mass is doubled but both the angle and coefficient of friction remain the same. In this case, the block has a nonzero acceleration down the incline.
(T) True
(F) False
14. A truck is traveling at 7.5 m/s on a horizontal road. The brakes are applied and it skids to a stop in 2.0 s. The coefficient of kinetic friction between the tires and road is:
(a) 1.22
(b) 0.69
(c) 0.76
(d) 0.92
(e) 0.38
15. This and the following question concern the same physical situation.
A horizontal force of 10 N pushes a block against a vertical wall, holding it in place as shown in the figure. The coefficient of static friction between the block and the wall is A?µs = 0.59. How many different forces act on the block?
(a) 2
(b) 3
(c) 4
16. In the preceding problem, what is the maximum mass of the block such that it does not slip?
(a) 2.4 kg
(b) 9.8 kg
(c) 3.0 kg
(d) 0.6 kg
(e) 10 kg
17. This and the following two questions concern the same physical situation.
Block A of mass 50 kg rests on a horizontal frictionless tabletop. A horizontal string is attached to A and passes over a massless, frictionless pulley and attaches to block B of mass 30 kg, as shown in the figure. Block A is held in place by hand so that the whole system is at rest. What is the tension in the string?
(a) 108 N
(b) 123 N
(c) 168 N
(d) 147 N
(e) 294 N
18. The system is then released and allowed to move freely. Compared to the preceding problem, the tension in the string is now:
(a) greater
(b) less
(c) the same
19. Suppose instead that there is sliding friction between block A and the tabletop but that the system still moves freely. Compared to the preceding problem where the system moved freely without friction, the tension in the string is now:
(a) greater
(b) less
(c) the same
20. Consider two identical satellites, each in circular orbit around the earth but at different distances from the center of the earth. Which satellite has the higher speed?
(a) the one further from the center of the earth
(b) the one closer to the center of the earth
(c) they both have the same speed
21. A man lifts a bucket from a well at constant speed and does 20,000 J of work. If the well has a depth of 120 m, what is the mass of the bucket?
(a) 17 kg
(b) 9.8 kg
(c) 1 kg
(d) 20 kg
(e) 120 kg
22. A car manufacturer claims that a super sports car of mass 800 kg will accelerate uniformly from rest to a speed of 35 m/s in 8 s. What is the net work on the car during this acceleration?
(a) 800,000 J
(b) 6,400,000 J
(c) 0 J
(d) 64,000 J
(e) 490,000 J
23. This and the following question concern the same physical situation.
A 5.0 kg block is held at rest at the top of a rough incline that makes an angle of 30A?° with the horizontal. The total length of the incline is 2.5 m. The block is then released and slides at constant speed down the incline, reaching the bottom of the incline in 2 s. What is the work done by gravity on the block?
(a) 25 J
(b) 61 J
(c) 115 J
(d) 200 J
(e) 98 J
24. Suppose your answer to the preceding problem is W. How much work is done by friction?
(a) W
(b) -W
(c) no work is done by friction
25. Two blocks, one of mass M and the other of mass 2M, are on a horizontal frictionless surface and are initially at rest. Then each block is acted upon by the same constant force F and for the same time interval D t. At the end of the time interval, which block has the larger kinetic energy?
(a) The block of mass M.
(b) The block of mass 2M.
(c) The two blocks have the same kinetic energy.
26. A block of mass M = 3 kg with an initial speed V slides down a frictionless hill of vertical height H = 3 m, along a horizontal frictionless surface, then up a second frictionless surface, reaching a maximum height H1 = 5 m. What was the initial speed V?
(a) 3.9 m/s
(b) 5.7 m/s
(c) 6.3 m/s
(d) 8.6 m/s
(e) 10.1 m/s
27. A girl of mass 50 kg jumps off the bow of a 75-kg canoe that is initially at rest. If her velocity is 2.5 m/s to the right, what is the speed of the canoe after she jumps?
(a) 3.34 m/s
(b) 2.5 m/s
(c) 0.0 m/s
(d) 1.67 m/s
(e) 5.0 m/s
28. This and the following question concern the same physical situation.
A soccer ball of mass 0.45 kg is initially at rest when it is kicked by the kicker. The impulse imparted to the ball by the kicker is 9.0 N-s. What is the speed of the ball as it leaves the foot of the kicker?
(a) 25 m/s
(b) 18 m/s
(c) 20 m/s
(d) 5 m/s
(e) 9 m/s
29. If the foot of the kicker is in contact with the ball for 0.005 s, what is the average force exerted by the foot on the ball?
(a) 1800 N
(b) 0.045 N
(c) 90 N
30. This and the following question concern the same physical situation.
A 5.0-kg object moves to the right with a speed of 4.0 m/s and collides head-on with a 10-kg object, which is moving to the left with a speed of 3.0 m/s. The 10-kg object stops completely after the collision. You may assume that the only forces on the two objects are the forces they mutually exert on each other. With the positive direction to the right, the final velocity of the 5-kg object is:
(a) 8 m/s
(b) 6 m/s
(c) 3 m/s
(d) 2 m/s
(e) 4 m/s
31. Suppose instead that the two objects stick together after colliding. In what direction does the combined system move after the collision?
(a) To the left.
(b) To the right.
(c) The combined system is at rest.
32. Block A of mass 2 kg has an initial velocity of 4 m/s. It collides and sticks to block B, which has a mass of 6 kg and is initially stationary. The two blocks then move together along a rough horizontal surface, eventually coming to a stop. Assuming that no net external forces act on the blocks during the collision, what is the magnitude of work done by friction in bringing the combined blocks to a stop?
(a) 2 J
(b) 3 J
(c) 4 J
(d) 5 J
(e) 6 J
QUESTION 38***
This and the following question concern the same physical situation.
A ball of mass M is released from rest a height H above the floor and collides elastically with the floor. What is the magnitude of the impulse exerted by the floor on the ball during the collision?
(a) M sqrt(2gH)
(b) 2 M sqrt(2gH)
(c) 0
QUESTION 39**
Suppose instead that the ball is released from rest from the same height but sticks to the floor. Compared with the previous problem, the impulse exerted by the floor on the ball will now be
(a) the same.
(b) greater.
(c) less.
QUESTION 40*
An object initially at rest explodes into two equal pieces. Below are two possible pictures of the pieces after the explosion, where the arrows indicate the direction of the velocity of each piece. Which of these is possible?
(a) only A
(b) only B
(c) both A and B