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 108. The exam period was 90 minutes; the mean score was 81.5; the median score was 85. Click here to see page1 page2 of the formula sheet that came with the exam.

A 3 kg block is released from rest at the top of a frictionless ramp 1.5 meters long. The acceleration of the block is measured to be 3.8 m/s^{2}.

What is the angle θ of the ramp?

(a) θ = 12.1° (b) θ = 16.3° (c) θ = 22.8° (d) θ = 25.2° (e) θ = 37.4°

(a) 3.4 m/s (b) 4.7 m/s (c) 5.3 m/s

An elevator is traveling down toward the bottom floor at a rate of 3.8 m/s. As it nears the bottom floor, the brakes are applied and it slows down at a constant rate of 1.5 m/s^{2}.

What is the apparent weight of a 55 kg person in the elevator while the brakes are being applied?

(a) 330 N (b) 450 N (c) 540 N (d) 620 N (e) 750 N

(a) 2.6 m (b) 3.7 m (c) 4.8 m

(a) (b) (c)

A 3 kg block is connected to 5 kg block that is being pulled by a force to the right across a frictionless surface. The acceleration of the two blocks is observed to be 1.8 m/s^{2}.

What is the magnitude of the tension T in the string connecting the two blocks?

(a) 5.4 N (b) 9.0 N (c) 14.4 N

(a) 9.0 N (b) 14.4 N (c) 18.8 N

(a) W_{E} > W_{P} (b) W_{E} = W_{P} (c) W_{E} < W_{P}

(a) 1.7 s (b) 3.4 s (c) 5.1 s (d) 6.3 s (e) 7.2 s

Two blocks are connected by string over a massless frictionless pulley as shown in the figure to the right. Once released, the 7 kg block accelerates downward raising the 3 kg block up.

What is the acceleration of the 3-kg block?

(a) 2.9 m/s^{2} (b) 3.9 m/s^{2} (c) 6.9 m/s^{2} (d) 9.8 m/s^{2} (e) 14 m/s^{2}

(a) |F_{3}| > |F_{7}| (b) |F_{3}| = |F_{7}| (c) |F_{3}| < |F_{7}|

A box of mass M = 7 kg is pulled across a horizontal floor at constant velocity. There is friction between the box and the floor. As shown in the figure, the force F makes an angle θ = 64° with the horizontal and the friction coefficient between the box and the floor is μ = 0.1.

What is the magnitude of the normal force on the box compared to the weight of the box, Mg ?

(a) smaller than Mg (b) equal to Mg (c) larger than Mg

(a) F = 5 N (b) F = 13 N (c) F = 27 N (d) F = 31 N (e) F = 44 N

A bird is resting on a phone wire between two poles that are 30 m apart. The bird is exactly midway between the two poles. Because of the weight of the bird, the wire sags by 50 cm. The tension in the wire is 70 N. (The mass of the wire is negligible.)

What is the mass of the bird?

(a) 121 g (b) 232 g (c) 365 g (d) 476 g (e) 554 g

(a) smaller than 70 N. (b) equal to 70 N. (c) larger than 70 N.

A car is going at constant speed, v = 45 m/s, on a circular race track. The radius of the track is R = 270 m.

How long does it take the car to travel one lap?

(a) t = 18.8 s (b) t = 24.4 s (c) t = 37.7 s

(a) 3.1 m/s^{2} (b) 4.2 m/s^{2} (c) 5.3 m/s^{2} (d) 6.4 m/s^{2} (e) 7.5 m/s^{2}

(a) μ = 0.53 (b) μ = 0.61 (c) μ = 0.77 (d) μ = 0.89 (e) μ = 0.93

(a) smaller than μ. (b) equal to μ. (c) larger than μ.

Eddy throws a little sand bag so that it lands on the top of a vertical post that is 4 m high. The post is 1.3 m away from Eddy. He releases the bag from a height of 1.5 m above the ground, as shown in the figure. The initial speed of the bag is v = 7.5 m/s, the angle, θ, between the velocity and the horizontal is θ = 80°. You can neglect the friction due to the air.

How long does the sand bag stay in the air?

(a) t = 0.7 s (b) t = 1.0 s (c) t = 2.5 s

(a) H = 4.3 m (b) H = 4.7 m (c) H = 5.2 m

(a) 0.0 m/s (b) 0.3 m/s (c) 1.4 m/s (d) 1.9 m/s (e) 2.7 m/s

Tarzan is trying to cross a river that is flowing at a speed v_{river}. Jane is waiting for him on the other side of the river, exactly across from him. Tarzan swims at a speed of 4 m/s. He determines that in order to swim straight to Jane, he needs to swim at an angle θ = 22°, as shown in the figure.

What is the speed of the river?

(a) v_{river} = 1.5 m/s (b) v_{river} = 2.6 m/s (c) v_{river} = 3.7 m/s (d) v_{river} = 4.8 m/s (e) v_{river} = 5.9 m/s

(a) W = 100 m (b) W = 220 m (c) W = 350 m (d) W = 450 m (e) W = 510 m