PHYS 250 Exam 2 Additional Practice Questions
You are to fill in the circle that corresponds to your answer for each question in
numbers 1 through 4.
1. A non-zero net force acts on an object that moves at constant velocity.
⃝
True
⃝
False
2. In a certain particle accelerator, a proton accelerates at 9.0 × 1013 m/s2. The
proton has a mass of 1.67x10-27 kg. What is the magnitude of the net force on the
proton?
⃝ 1.9x10 -41 N
⃝ 5.4x10 40 N
⃝ 6.7x10 12 N
⃝ 1.5x10 -13 N
3. The coefficient of rolling friction is 0.80 between a beach ball and sand. The
wind blows the ball across the sand. The sand exerts a 0.74-N normal force on the
ball. What is the magnitude of the friction force acting on the ball?
⃝ 0.59 N
⃝ 0.93 N
⃝ 1.1 N
⃝ 5.8 N
⃝ 7.8 N
4. What is the mass of an object that experiences a gravitational force of 685 N
near Earth's surface where g = 9.80 m/s2?
⃝ 69.9 kg
⃝ 68.5 kg
⃝ 71.3 kg
⃝ 72.7 kg
The following statement applies to questions 5 and 6.
An object that weighs 75 N is pulled to the right on a horizontal surface by a 65 N force
directed 35° above horizontal. The friction force on this object is 30 N to the left.
5. Draw the situation on the left and the object’s free body diagram on the right in the
box below.
6. What is the acceleration of the object?
Show your answer in the box to the right.
Show your formula(s) in the box below.
7. A 55-kg box rests on a horizontal surface. The coefficient of static friction
between the box and the surface is 0.30. What is the maximum horizontal force
that can be applied to the box without it beginning to slide (move)?
Show your answer in the box to the right.
Show your formula(s) and calculations in the box below.
8. What magnitude net force is required to accelerate a 1200-kg car uniformly
from 0 m/s to 27.0 m/s in 10.0 s?
Show your answer in the box to the right.
Show your formula(s) and calculations in the box below.
9. A 45.0-kg person steps on a scale in an elevator. The scale reads 460 N. What is
the magnitude of the acceleration of the elevator?
Show your answer in the box to the right.
Show your formula(s) and calculations in the box below.
10. A purple penguin pulls to the right on a green gopher with a force of 27 N
using a rope tied to the gopher. Identify the reaction force to the penguin’s pull.
Include the type of force, its magnitude, its direction, and the object it acts on.
Show your answer in the box below.
11. The green gopher in question 10 has a mass of 6.6 kg and experiences a
friction force of 18 N due to the ground. What is the acceleration of the gopher?
Show your answer in the box to the right.
Show your formula(s) and calculations in the box below.
12. What is the coefficient of kinetic (sliding) friction between the gopher and the
ground in question 11?
Show your answer in the box to the right.
Show your formula(s) and calculations in the box below.
13. An object is being acted upon by three forces and moves with a constant
velocity. One force is 60 N along the +x-axis, the second is 75 N along a direction
making a counterclockwise angle of 150° with the +x-axis. What are the
magnitude and direction of the third force?
Show your answer in the box to the right.
Show your formula(s) and calculations in the box below.
PHYS 250 Exam 2 Additional Practice Questions - Answers
1. False
2. 1.5*10-13 N
3. 0.59 N
4. 69.9 kg
5. See solutions
6. 0.31 m/s2 horizontally opposite the friction force
(+ x-direction in drawing in #5.)
7. 0.16 kN horizontally opposite the friction force
8. 3240 N ≈ 3.2 kN
9. 0.42 m/s2
10. Reaction force is a tension force of 27 N to the left on the purple penguin
11. 1.4 m/s2 to the right
12. 0.28
13. 38 N at -82o