SPH3U Exam Review: Forces and Motion
Multiple Choice
1.
The property of matter that causes an object to resist changes in its state of motion is called:
A. friction
2.
D. tension
B. velocity
C. both A and B
D. neither A nor B
C. Newton
D. pound
The SI unit for weight is the:
A. Joule
4.
C. the normal force
If the net force on an object is increased, the magnitude of its ______________ increases.
A. acceleration
3.
B. inertia
B. kilogram
The jerking you feel when the vehicle in which you are riding is stopped suddenly is best
explained using which of Newton's Laws?
A. Newton's 1st Law B. Newton's 2nd Law C. Newton's 3rd Law D. Universal Gravitation
5.
An object of mass 4 kg is travelling at a constant velocity of 2 m/s [E]. What is the net force
on the object?
A. 0 N
6.
C. 8 N [E]
D. It cannot be determined.
If the distance between two objects is halved the gravitational attraction between them is:
A. the same
7.
B. 2 N [E]
B. doubled
C. halved
D. quadrupled
Which of Newton's Laws of Motion applies to objects in outer space?
A. Newton's 1st Law B. Newton's 2nd Law C. Newton's 3rd Law D. all of the above
8.
A magnet is sliding down a fridge door. What is the direction of the normal force acting on
the magnet?
A. up
9.
D. out of the door
B. 10 N
C. 20 N
D. 30 N
Object A of mass 2 kg is attached to Object B of mass 4 kg by a string suspended over a pulley.
The tension in the part of the string attached to Object A is __________ the tension in the part
of the string attached to Object B.
A. the same as
11.
C. into the door
A book of weight 20 N is resting on a table. If a horizontal force of 10 N [right] is applied to
the book, the magnitude of the normal force acting on the book will be:
A. 0 N
10.
B. down
B. less than
C. greater than
D. It cannot be determined.
An object of weight 40 N is being pushed at constant velocity across a surface with a force of
10 N [right]. What is the force of friction acting on the object?
A. 10 N [down]
B. 10 N [left]
C. 50 N [down]
D. 50 N [left]
12.
A book is resting on a table. The Earth is exerting a gravitational force of 8 N [down] on the
book. Which of the following is the reaction force?
A. 8 N [up] the table exerts on the book
C. 8 N [up] the book exerts on the Earth
13.
A block of weight 4.0 N is suspended from the ceiling of an elevator by a piece of string.
If the elevator is accelerating at 1.0 m/s2 [down], the magnitude of the tension in the string is:
A. zero
14.
B. less than 4.0 N
C. 4.0 N
D. greater than 4.0 N
Fuzzy dice are hanging from the rear-view mirror of a car that is travelling backward at
constant speed. The dice are:
A. angled toward the back of the car
C. hanging straight down
15.
B. 8 N [down] the book exerts on the table
D. There is no reaction force.
B. angled toward the front of the car
D. It cannot be determined.
Running shoes are designed to do what to the force of friction between the runner and the
ground?
A. increase
B. decrease
C. neither A nor B
D. alternately A and B
Short Answer
1.
A sled is being pulled rightward across a surface by a horizontal rope tied to it. Draw the FBD
for the sled.
2.
If the rope is at an angle above the horizontal, how will the other forces on the sled be
affected? Explain why.
3.
What is the net force acting on the sled? Explain why it is impossible to describe the motion
of the sled without more information.
Problem Solving
1.
A 0.40-kg cart on a table is attached by a string to a suspended mass of 0.25-kg. A
frictional force of 1.2 N opposes the motion of the cart. What is (a) the magnitude of the
acceleration of the cart and (b) the tension in the string between the cart and the mass?
2.
A box of mass 15 kg slides across a floor and comes to a complete stop. Its initial speed was
4.2 m/s and µk = 0.30. Find (a) the acceleration of the box and (b) the distance travelled by the
box before stopping.
3.
Two skaters are standing on ice facing each other. Skater 1 pushes on skater 2 with a force of
70.0 N [E]. The coefficient of friction between the skaters and the ice is 0.10. The mass of
skater 1 is 50.0 kg and the mass of skater 2 is 70.0 kg. Calculate the acceleration of each
skater.