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 102. When the exam was given, the mean was 76.4; the median was 79. Click here to see page1 page2 of the formula sheet that came with the exam.

A box is pulled across a horizontal surface at a constant speed by a horizontal rope with tension T = 30 newtons. The coefficient of friction between the box and surface is μ_{k }= 0.05.

Calculate the work done by friction as the box moves 4 meters to the right.

(a) -120 J (b) -30 J (c) -1.5 J

(a) 31 kg (b) 61 kg (c) 121 kg (d) 25 kg (e) 27.4 kg

(a) positive. (b) zero. (c) negative.

Two 0.025 kg balls are released at rest from a height h above the ground. Both balls are traveling at 5 m/s just before they hit the ground. Ball 1 is a steel ball, and bounces back up to the original height. Ball two is made of clay and sticks to the floor.

Which ball exerts a greater impulse on the floor?

(a) clay ball (b) same (c) steel ball

(a) 1.28 m (b) 2.15 m (c) 2.89 m

(a) 0.011 s (b) 0.017 s (c) 0.025 s

(a) smaller than 15 N. (b) equal to 15 N. (c) larger than 15 N.

A box starts from rest and slides down a hill of height h. Friction is negligible. When it reaches the point marked A, it collides with a stationary box with three times its mass. The two boxes stick together and slide to the right. The speed of the first box is 15 m/s just before the collision.

What is the height h of the hill?

(a) 3.8 m (b) 6.2 m (c) 9.7 m (d) 11.5 m (e) 17.3 m

(a) K_{initial} > K_{final} (b) K_{initial} = K_{final} (c) K_{initial} < K_{final}

(a) 15 m/s (b) 7.5 m/s (c) 5 m/s (d) 3.75 m/s (e) 0 m/s

Two disks are on a frictionless plane as shown. The first disk, with mass M is initially at rest. The second disk with mass 2M has an initial velocity of 6 m/s in the y direction before colliding with the first disk.

After the collision, the disk with mass 2M is deflected 15° and has speed 3 m/s as shown in the figure. (Ignore the effects of gravity, all the pieces are moving in a horizontal plane, and you may neglect friction).

What is the x component of the velocity of disk 1 (mass M) after the collision?

(a) 0.78 m/s (b) 1.55 m/s (c) 3.10 m/s (d) 6.20 m/s (e) 12.4 m/s

(a) I_{1} < I_{2} (b) I_{1} = I_{2} (c) I_{1} > I_{2}

(a) only kinetic energy (b) only momentum (c) both kinetic energy and momentum

In yet another experiment gone wrong, a rocket car built by Dr. Olaf Whatanut exploded into three pieces. The first two pieces have a mass M_{1} = 95 kg , and M_{2} = 50 kg, respectively. The device was originally at rest. Piece one was observed heading exactly North West at 150 mph. Piece 2 was observed heading exactly North East at 285 mph. Dr. Whatanut is inside piece 3, which has a total mass of M_{3} = 250 kg. (Ignore the effects of gravity, all the pieces are moving in a horizontal plane, and you may neglect friction).

The total kinetic energy of the system after the collision is zero.

(T) True (F) False

(a) southeast (b) southwest (c) due south

(a) 54 mph (b) 60 mph (c) 81 mph (d) 92 mph (e) 125 mph

A street lamp of mass M = 5 kg is suspended from the end of a rod of length L = 1.0 m and mass m = 1.5 kg. The rod is supported by a cable attached to its midpoint and by a pivot at the wall. The cable makes an angle θ = 45° with the rod, and has negligible mass.

What is the magnitude of the tension in the cable?

(a) T = 130 N (b) T = 140 N (c) T = 150 N (d) T = 160 N (e) T = 170 N

The tension in the cable in this new situation is

(a) larger than in the previous case. (b) the same as the previous case. (c) smaller than the previous case.

The relationship between the moments of inertia for rotations about the axes shown is:

(a) I_{A} > I_{B} (b) I_{A} = I_{B} (c) I_{A} < I_{B}

A torque wrench is used to tighten nuts (such as the ones that hold the wheels on a car) to a specific value of torque.

If a torque of 85 Nm is required and the wrench handle is 1.5 m long, how much force must be applied to the end of the wrench?

(a) 128 N (b) 85 N (c) 57 N

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

A large crane used in construction uses a counter weight M to balance the weight m that is to be moved. The center of mass (CM) of the uniform beam is located 2.25 m from the support as shown. The mass of the beam is 300 kg,

If m = 1200 kg, what mass should M be such that the crane is in static equilibrium in the horizontal position?

(a) 1500 kg (b) 3340 kg (c) 3938 kg (d) 6680 kg (e) 3900 kg

(a) M was moved closer to the support point. (b) M was moved further from the support point.

If the block starts a rest, what is the speed of the block after it drops by 5 m?

(a) 11.3 m/s (b) 9.9 m/s (c) 9.0 m/s (d) 8.1 m/s (e) 7.2 m/s