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 125. The exam period was 90 minutes; the mean score was 83.6; the median score was 85. Click here to see page1 page2 of the formula sheet that came with the exam.

A physics 101 student weighs 600 N on Earth. She travels in her spaceship to mysterious planet X which has a radius r_{X} that is twice the radius of Earth, r_{X} = 2r_{E}. On the surface of planet X, she finds that she weighs 300 N.

Relative to Earth's mass, m_{E}, what is the mass of planet X?

(a) 0.25m_{E} (b) 0.5m_{E} (c) 1.0m_{E} (d) 2.0m_{E} (e) 4.0m_{E}

(a) g_{X} > g_{E} (b) g_{X} = g_{E} (c) g_{X} < g_{E}

Ralph is using the pulley system shown in the picture to hold a 45 kg mass stationary.

What is the force exerted by the ceiling?

(a) 222 N (b) 442 N (c) 662 N (d) 882 N (e) 1100 N

(a) f_{H} = T / 3 (b) f_{H} = T (c) f_{H} = 3 T

A physics book of mass 2 kg is sitting atop a table with coefficient of static friction μ_{s} = 0.4 and coefficient of kinetic friction μ_{k} = 0.3. A person is pushing the book as shown in the figure.

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

(a) 2.0 N (b) 4.1 N (c) 5.7 N (d) 6.6 N (e) 7.8 N

(a) (b) (c)

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

Three boxes of equal mass, m, are connected to one another by strings as shown in the figure. They are pulled across a frictionless surface by tension T_{1}.

Which of the three boxes has the largest net force acting on it?

(a) box 1 (b) box 2 (c) box 3 (d) boxes 1 and 3 (e) All three boxes have the same net force acting on them.

(a) a = T_{1} / m (b) a = T_{1} / (2m) (c) a = T_{1} / (3m) (d) a = 2 T_{1} / m (e) a = 3 T_{1} / m

Professor Pitts pushes on a cart of mass 50 kg with a horizontal force F_{push}. There is no friction. The cart has an acceleration of 5 m/s^{2}.

Which one of the following statements is true?

(a) By Newton's third law, the cart applies an equal and opposite force of magnitude F_{push} on Professor Pitts. (b) The cart applies an opposite force on Professor Pitts, but it is smaller in magnitude than F_{push} because of the acceleration force. (c) The force the cart applies on Professor Pitts is responsible for the acceleration of the cart. (d) The cart applies no force on Professor Pitts, because it is not pushing back on him. (e) The cart applies an opposite force on Professor Pitts and it is larger in magnitude than F_{push}.

(a) 1 N (b) 10 N (c) 100 N (d) 250 N (e) 980 N

A block of mass m_{1} = 5 kg sits atop a frictionless incline which makes and angle θ = 25° as shown in the figure.

What is the acceleration of the block?

(a) 1.1 m/s^{2} (b) 2.1 m/s^{2} (c) 4.1 m/s^{2} (d) 9.8 m/s^{2} (e) 11.1 m/s^{2}

(T) True (F) False

(a) m_{1} wins. (b) m_{2} wins. (c) It's a tie: the two masses arrive at the same time.

This and the following question concern the same physical situation.

You are trying to shoot a monkey hanging on a tree branch using a toy cannon. You aim directly at the monkey and fire the cannon with a speed v and at an angle of 30° relative to the x direction. At the same time, the monkey lets go of the tree branch and fall toward the ground due to gravitational force. We ignore air resistance in this problem. The distance between the cannon and the tree is 50 m in the x direction.

The cannon ball hits the monkey 2 seconds later after the shot was fired. What was the initial speed of the cannon ball v?

(a) 28.9 m/s (b) 25.3 m/s (c) 22.1 m/s (d) 20.0 m/s (e) 18.9 m/s

(a) 9.8 m (b) 19.6 m (c) 25.4 m

There is a box with a total mass of 1 kg sitting on the floor of an elevator located in the middle of a vertical shaft. The elevator is free to move upward or downward. When the elevator is at rest, it takes a horizontal force of 4 N to make the box start to slide.

The elevator is now moving vertically (without friction). It takes 5 N of horizontal force to make the box start to slide. What can you say about the direction of elevator's motion?

(a) It is going up. (b) It is going down. (c) Not enough information is given to determine in which direction the elevator is moving.

(a) 5.22 N (b) 4.6 N (c) 4 N (d) 3.4 N (e) 2.78 N

An airplane is flying due east relative to the air at a speed of 200 m/s.

The wind is blowing at 30 m/s toward the east relative to the ground. (With the wind), it takes 1.5 hours to fly from point A to point B, where point B is due east of point A. Under this condition, how long will it take to fly from point B to point A?

(a) 1.3 hours (b) 2.0 hours (c) 1.7 hours (d) 1.85 hours (e) 1.6 hours

(a) 173 m/s (b) 180 m/s (c) 202 m/s (d) 222 m/s (e) 231 m/s

You are flying on an airplane flying due east at a speed of 50 m/s and at an altitude of 1,000 m, and drop an apple of 0.1 kg in mass. Ignore air resistance for this problem. And there is no wind.

What is the speed of the apple when it hits the ground?

(a) 149 m/s (b) 86 m/s (c) 140 m/s (d) 50 m/s (e) 177 m/s

(a) 2.9 s (b) 9.8 s (c) 11.8 s (d) 14.3 s (e) 21.7 s

Which is the appropriate relationship between force pulling the cart (F), the mass of the cart (M), the mass of the weight (m), and acceleration of the cart (a)?

(a) F = mg = Ma (b) F= (m+M)g = ma (c) F= (m+M)g = Ma (d) F = M= Ma (e) F= mMg/(m+M) = Ma

The diagram below is a graph of Mary walking on a runway. The detector is at zero position and velocity. The direction away from the detector is positive. Note: in reality, a person may not be able to exactly reproduce this.

Where is Mary accelerating?

(a) B, D, F (b) A, C, E, G (c) D

(a) infinity (b) negative infinity (c) 0

(a) In B she is moving towards the detector while in D she is moving away from the detector. (b) There is no difference. (c) In B she is rapidly speeding up, till the point where she is moving away from the detector at constant speed, whereas in D she is rapidly changing direction until she is going at a constant speed walking towards the detector.