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 110. The exam period was 90 minutes; the mean score was 79.2; the median score was 82. Click here to see page1 page2 of the formula sheet that came with the exam.

What is the magnitude of the force F provided by Amelia's hand necessary to keep the 45 kg mass stationary?

(a) 221 N (b) 442 N (c) 662 N (d) 882 N (e) 1100 N

(a) 0.21 s (b) 0.45 s (c) 0. 85 s (d) 1.25 s (e) 1.56 s

(a) g (b) g cosΦ (c) g sinΦ

A cart is moving along the x-coordinate. It's x-coordinate as a function of time is measured every second and is shown below.

The average velocity between 0 and 7 seconds is

(a) negative. (b) positive.

A cellular motor protein called myosin V can carry cargos and move on a straight cellular track called actin filament. Researchers in the Physics Department at the University of Illinois measured the position of a single myosin V molecule along an actin filament a function of time as shown below.

What is the magnitude of the average velocity between 0 second and 70 second? (1 nm is 10^{-9} m.)

(a) 1.5 nm/s (b) 2.7 nm/s (c) 5.9 nm/s (d) 7.4 nm/s (e) 12.1 nm/s

(a) 0 nm/s (b) - 40 nm/s (c) + 40 nm/s (d) - 400 nm/s (e) + 400 nm/s

(a) yes (b) no

A steel block of mass 3 kg is sitting atop a horizontal table with coefficient of static friction μ_{s} = 0.35 and coefficient of kinetic friction μ_{k} = 0.25 . Professor Ha is pushing the book as shown in the figure.

If the block is at rest, how hard can he push on the block before it will start moving?

(a) 2.0 N (b) 4.1 N (c) 5.7 N (d) 7.4 N (e) 10.3 N

(a) 3.3 m (b) 2.3 m (c) 1.8 m (d) 1.5 m (e) 1.2 m

(a) 137 km/hr (b) 200 km/hour (c) 223 km/hour (d) 280 km/hour (e) 300 km/hour

Consider two Blocks, Block A = mass M, and Block B = mass m, connected with a weightless string through a weightless and frictionless pulley as shown in the figure. Block A is on a table which is horizontal. The coefficient of static friction between Block A and the table is μ_{s} = 3/5. Let g be the acceleration of gravity.

Assume that m = M/3 and that the masses are static. What is the friction force f on Block A from the table?

(a) f = Mg / 5 (b) f = Mg / 3 (c) f = 3Mg / 5 (d) f = 2Mg / 3 (e) f = Mg

(a) The acceleration is much smaller than g. (b) The acceleration is almost g. (c) The acceleration is much larger than g.

A box of mass M is sitting on a scale in an elevator. Initially, the elevator is stationary (is not moving relative to the earth). Let g be the acceleration of gravity.

When the elevator starts to move, the reading of the scale becomes 1.1 times M (that is, 1.1M). What can you say about the motion of the elevator immediately after it starts to move?

(a) The elevator is going upward. (b) The elevator is going downward. (c) Not enough information to tell the direction.

(a) |a| = g / 20 (b) |a| = g / 10 (c) |a| = g / 7 (d) |a| = g / 4 (e) |a| = g / 3

(a) The elevator is going upward. (b) The elevator is going downward. (c) There is not enough information to tell the direction.

There are three boxes on a frictionless horizontal surface as illustrated in the following figure. The masses of the two left boxes are M (identical) and the mass of the rightmost box is 12 kg. A person pushes the leftmost box to the right with a force F. Consequently, all the boxes are accelerated to the right.

The rightmost box of mass 12 kg pushes the middle box with a force whose magnitude is 240 N. What is the magnitude of the force the middle box exerts on the rightmost box?

(a) 12 kg (b) 24 kg (c) 120 N (d) 240 N (e) 480 N

(a) M = 2.0 kg (b) M = 4.0 kg (c) M = 4.5 kg (d) M = 6.5 kg (e) M = 7.5 kg

(a) X_{H} = V^{2} / 2g (b) X_{H} = V^{2} / g (c) X_{H} = 2V / g (d) X_{H} = V / g (e) X_{H} = V / 2g

(T) True (F) False

A small coin of mass M is just inside the edge of a rotating horizontal circular stage of radius R as illustrated below. The coefficient of static friction between the coin and the stage floor is μ_{s}.

What is the angular speed ω of the circular stage beyond which the coin cannot stay on the edge of the stage?

(a) (b) (c) (d) (e)

(a) (b) (c)

A cart is pushed up a ramp with force F in the presence of friction. At some point the force is suddenly turned off. It reaches some height, then rolls down. (Our sign convention is the positive direction is up.)

The velocity is:

(a) v > 0 on the way up, zero at the top, and then v > 0 on the way down. (b) v > 0 on the way up, zero at the top, and then v < 0 on the way down. (c) v < 0 on the way up, zero at the top, and then v < 0 on the way down.

(a) a > 0 on the way up, zero at the top, and then a > 0 on the way down. (b) a > 0 on the way up, zero at the top, and then a < 0 on the way down. (c) a < 0 on the way up, zero at the top, and then a< 0 on the way down. (d) a < 0 at all times but of greater magnitude when going up than coming down. (e) a < 0 at all times but of greater magnitude when going down than coming up.