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 114. The exam period was 90 minutes; the mean score was 81.7; the median score was 83. Click here to see page1 page2 of the formula sheet that came with the exam.

The position vs time and velocity vs time diagrams for a block on a surface are shown at right.

What is the instantaneous velocity at t = 0.5 seconds?

(a) 31.4 m/s (b) -31.4 m/s (c) 0 m/s (d) 5 m/s (e) -5 m/s

(a) 126 m/s^{2} (b) -126 m/s^{2} (c) 0 m/s^{2} (d) 31.4 m/s^{2} (e) -31.4 m/s^{2}

(a) 9.8 m/s^{2} (b) -9.8 m/s^{2} (c) 0 m/s^{2} (d) 1.5 m/s^{2} (e) -1.5 m/s^{2}

(a) 9.2 m/s (b) 7.7 m/s (c) 6.6 m/s (d) 3.0 m/s (e) 2.2 m/s

(a) 5.1 m (b) 7.9 m (c) 11.7 m (d) 12.9 m (e) 13.4 m

A train is braking from an initial speed of 100 m/s. The train is braking hard, so the wheels are sliding over the rails. The coefficient of kinetic friction between the rail cars and the rails is μ_{k} = 0.1 . How long will it take the train to stop?

(a) 10 s (b) 23 s (c) 37 s (d) 43 s (e) 102 s

(a) F_{1-2} = F_{9-10} (b) F_{1-2} = 9 F_{9-10} (c) F_{1-2} = 10 F_{9-10}

Bob is standing on the floor of a cart that is moving horizontally at a constant speed v = 3 m/s. Ignore air resistance. The length of the cart L = 2 m and he is at the center point B of the cart.

Bob jumps straight up relative to the coordinate system of the moving cart with an initial speed of 4 m/s. What is the maximum distance between his foot and the cart floor? You may assume that his feet and other body parts move rigidly together.

(a) 0.35 m (b) 0.57 m (c) 0.64 m (d) 0.82 m (e) 0.97 m

(a) A (b) B (c) C

Suppose you are driving over a hill at constant speed v. The hill is roughly circular very close to and beyond the top, as shown in the figure.

If your mass is M, what relation does the magnitude of your apparent weight (i.e., the normal force F exerted on you by the car seat) have to the gravitational force on you as you drive over the top of the hill?

(a) F = Mg + Mv^{2}/R (b) F = Mg (c) F = Mg - Mv^{2}/R

(a) yes (b) no

(a) R is approximately 100 m. (b) R is approximately 80 m. (c) R is approximately 60 m.

This and the following question concern the same physical situation.

Audio CD players read the data on the disc at a constant linear speed and thus must vary the disc's rotational speed as the reading position moves from the inner edge to the outer edge. The radius of the innermost track is 25 mm and the rotational speed of the disk when the innermost track is read is 8 turns per second.

What is the required angular speed of the disk when the outermost track, whose radius is 58 mm, is read at the same rate as the innermost track?

(a) 18.7 rad/s (b) 21.7 rad/s (c) 24.7 rad/s (d) 28.7 rad/s (e) 35.7 rad/s

(a) 7.60 rad/s^{2} (b) 9.70 rad/s^{2} (c) 11.6 rad/s^{2} (d) 13.0 rad/s^{2} (e) 15.6 rad/s^{2}

(a) 28.2 m/s (b) 32.5 m/s (c) 34.1 m/s (d) 35.9 m/s (e) 40.0 m/s

(a) The object must stand still (cannot be moving). (b) The object will have a constant velocity. (c) It is possible that the object may accelerate.

(a) If one block is pulling the other, then the pulling block exerts a greater force. (b) The forces are zero if the blocks are not moving. (c) The forces are equal in magnitude and opposite in direction.

(a) approximately 49 N. (b) approximately 99 N. (c) approximately 198 N. (d) zero, because the masses are not moving. (e) none of the above

(a) 3 kg (b) 5 kg (c) 8 kg (d) 10 kg (e) 13 kg

(a) 0.05 m/s^{2} (b) 0.2 m/s^{2} (c) 2 m/s^{2} (d) 20 m/s^{2} (e) 50 m/s^{2}

A block of wood is pulled on a flat surface with a horizontal force F_{1} at steady velocity of V_{1}. There is friction between the block and the surface. Now another block of wood (identical) is added on top of the original block. With what force F_{2} must one pull so that the stacked blocks travel at a constant velocity?

(a) F_{2} = F_{1} (b) F_{2} = 2F_{1} (c) F_{2} = F_{1} / 2 (d) One cannot tell without knowing the value of the frictional coefficient of kinetic friction. (e) One cannot pull a block at constant velocity on the surface with a constant force; it will always accelerate.

(a) The block moves. (b) The block does not move.