Physics 114 Final Mathematics & Economics Coursework

For problems with numerical solutions you must show all your work and box your answers.
Each problem or problem part is worth 1 point.
Don't forget to sign your exam as a pledge to do your own work.

Name _________________

Upload your exams to Canvas by the end of the day on Friday, March 20th.

For problems with numerical solutions you must show all your work and box your answers.

Each problem or problem part is worth 1 point.

Don't forget to sign your exam as a pledge to do your own work.

PHYS 114 A, Final Exam

Part I:  True and False questions (1 point each).  Circle the best answer.

• Momentum is not conserved during a collision.

True or False

• Energy is conserved during perfectly elastic collisions.

True or False

• Power is measured in Watts = kg m²/s³.

True or False

4.   If a net force acts on a system of particles, the momentum of the system of particles will not change.

True or False

5.   Work is done when the force and the displacement are perpendicular.

True or False

6.   If an object moves in the negative x-direction its kinetic energy is negative.

True or False

7.   If the work done on an object is negative the force and displacement are in opposite directions.

True or False

8.   The change in gravitational potential energy of an object can never be negative.

True or False

9.   A Cadillac and a semi-truck collide with one another, lock bumpers, and stick together after the crash.  This is an example of a maximally inelastic collision.

True or False

10.  In order to do the maximum possible work on an object you should exert your force in the direction of the object’s displacement.

True or False

Part II:  Multiple-choice questions (1 point each) Circle the best answer.

• If the velocity of an object increases by a factor of four, the kinetic energy of the object

(a) increases by a factor of 2.

(b) increases by a factor of 4.

(c) increases by a factor of 8.

(d) increases by a factor of 16.

(e) decreases by a factor of ¼.

• A net force of 200 N acts on a 100 kg boulder, and a force of the same magnitude acts on a 100 g pebble.  Which of the following explanations provides the best description of the objects behavior after the force is applied for one second.

• The large mass of the boulder gives it a greater change in momentum.


• The force results in a greater speed for the 100 g pebble, but the change in momentum is the same for both.

(c) The force results in a greater speed for the 100 g pebble, resulting in a greater change in momentum.

(d) The force causes a much smaller speed in the boulder, resulting in a smaller change in momentum.

(e) The small mass of the pebble gives it a smaller change in momentum.

• The barricade at the end of a subway line has a large spring designed to compress 2.00 m when stopping a 1.65 x 10⁵ kg train moving at 0.510 m/s.  What is the force constant of the spring?

• 5600 N/m        b)   7080 N/m      c)   8090 N/m        d)   9500 N/m     e)  10700 N/m

• An object moving at a constant speed along a circular path has

(a)  no net force acting on it.

(b) a net force acting in the direction of its motion.

(c) a net force acting on it.

(d) kinetic energy that changes with time.

(e) a constant momentum.

• When a golf club strikes a golf ball, the magnitude of the change in momentum of the ball is _________ compared to the magnitude of the change in momentum of the club.

• less than       b) equal to                 c) greater than      d) it depends on the type of collision

6.   From a physics perspective, a pole-vaulter would rather land on mat instead of concrete for which of the following reasons?

(a)  Their change in momentum is less resulting in less net force.

(b) Their change in energy is less resulting in less net force.

(c) Their change in momentum is greater resulting in a larger net force.

(d) Their change in momentum is the same for each case, but the force by the mat acts over a longer interval of time reducing the force on the pole-vaulter.

(e) Their change in energy is the same for each case, but the mat does less work on the pole-vaulter than the concrete.

7.  You walk on top of a sled that is free to move on a flat icy road.

• The sled does not move while you are walking.


•  The sled ceases to move once you obtain a constant speed.


• The sled moves with a velocity equal and opposite to your velocity.


• The sled moves with a momentum equal and opposite to your momentum.


• The motion of the sled can only be determined if energy is conserved.

8.  A physics TA pushes a 20.0 kg cart at a constant velocity 22.0 m down the hall. The force she exerts on the cart is directed at an angle 26.0° below the horizontal, and the force of friction opposing the motion of the cart is 44.0 N. What is the total work done on the cart?

• 0 J       b)   460 J         c)  607 J           d)  968 J          b) 1040 J

9.  A force of constant magnitude pushes a box up a vertical surface, as shown in the figure.

The box moves at a constant speed. If the mass of the box is 4.0 kg, and it is pushed 2.2 m vertically upward, the coefficient of friction is 0.35, and the angle θ is 37°.  What is the work done by the force, F?  Use g = 10 m/s².

• 165 J               b)   205 J         c)  246 J          d) 290 J                       e) 325 J                      

10.  A cheetah can go from rest to 7.4 m/s (about 17 mi/h) in 1.1 s. If its mass is 51 kg, what is the average power developed by the cheetah during the acceleration phase of its motion?

• 1300 W                       b) 1500 W         c)   1900 W        d) 2200 W         e) 2600 W

Part III:  Open Response (1 point for each part)

•  A 1.3 kg block rests on a spring, k = 640 N/m, compressed by a distance d = 0.11 m.  If you assume the track is nearly frictionless, with the exception of a rough patch at the end, determine the following.

• The potential energy stored in the spring.


• The speed at which the block reaches the top of the ‘approximately’ circular mound.


• Draw and label a free-body diagram for the block at the top of the mound.


• The normal force at the top of the mound.


• The distance along the rough surface required to stop the block.

2.  Two gliders, with the same mass of 1.2 kg, collide on a nearly frictionless air track with two different results as shown below.  In Case 1 the velocity of glider 1 is to the left after the collision, the velocity of glider two is not given. In Case 2 the velocity of glider 1 is zero after the collision, the velocity of glider two is not given.

• If the momentum of the system before the collision is 6.4 kg m/s to the right.  Find the initial velocity of glider 1.


• The final speed of glider 1 in Case 1 is 2.2 m/s. Determine the final velocity of cart 2


• In which case is the change in momentum for glider 2 the greatest?  Explain briefly using a vector diagram showing the change in momentum for each case.


• Check your answer to (c) by calculating the change in momentum for glider 2 in both cases.


• One of the cases above is not physically possible.  Which one?  Justify your answer by comparing the kinetic energy of the system before and after the collision for each case.