This exam consists of 25 questions; true-false questions are worth 2 points each, three-choice multiple choice questions are worth 3 points each, five-choice multiple choice questions are worth 6 points each. The maximum possible score is 117. When the exam was given, the mean was 98.4; the median was 102. Click here to see the formula sheet that came with the exam.

(a) 17 kg (b) 9.8 kg (c) 1 kg (d) 20 kg (e) 120 kg

(a) 800,000 J (b) 6,400,000 J (c) 0 J (d) 64,000 J (e) 490,000 J

A 5.0 kg block is held at rest at the top of a rough incline that makes an angle of 30° 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

(a) W (b) -W (c) no work is done by friction

(a) The block of mass M. (b) The block of mass 2M. (c) The two blocks have the same kinetic energy.

(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

(a) (0, 0.33) (b) (0, 1) (c) (0.33,0) (d) (1,0) (e) (0,2)

(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

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

(a) 1800 N (b) 0.045 N (c) 90 N

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

(a) To the left. (b) To the right. (c) The combined system is at rest.

(a) 2 J (b) 3 J (c) 4 J (d) 5 J (e) 6 J

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

(a) the same. (b) greater. (c) less.

A mobile consists of two boxes hanging from a uniform massless rod of length L=2 m. One box, whose mass is 3 kg, hangs from the left end of the rod. The other box, whose mass is 1 kg, hangs from the right end of the rod. The rod itself hangs by a wire attached to the ceiling (see the picture below, not necessarily shown to scale) and attached to the rod a distance d from the left end. The whole system is in static equilibrium and gravity points downward. What is the tension T in the wire?

(a) 22.8 N (b) 39.2 N (c) 56.2 N (d) 74.1 N (e) 94.5 N

(a) 1.5 m (b) 1.0 m (c) 0.5 m (d) 0.25 m (e) 0.75 m

(a) larger (b) smaller (c) the same

An irregularly shaped object of weight 2 N is suspended vertically from the ceiling by a string attached to a pivot point P. The center of mass (CM) is located a distance 0.4 m below the pivot point and 0.3 m to the left of the pivot point. The system is not in static equilibrium. Gravity points downward. What is the torque on the object about the pivot point due to gravity?

(a) 0.6 N-m (b) 0.8 N-m (c) 1.0 N-m

Two children ride on a merry-go-round of radius R = 3 m that is rotating with a constant angular velocity about its center. Child 1 is located on the rim of the merry-go-round and child 2 is located halfway between the center and the rim. Which child has the larger centripetal acceleration?

(a) The one closer to the center. (b) The one further from the center. (c) They both have the same centripetal acceleration.

(a) 75 (b) 25 (c) 125 (d) 60 (e) 15

(a) 10 (b) 13 (c) 20 (d) 28 (e) 35

(a) The one closer to the center. (b) The one further from the center. (c) They both have the same tangential acceleration.

(a) 75 (b) 34 (c) 22 (d) 15 (e) 120

(a) only A (b) only B (c) both A and B