Download SPH3U Forces-and-Motion-Exam

SPH3U Exam Review
1. The property of matter that causes an object to
resist changes in its state of motion is called:
A. friction
B. inertia
C. the normal force
D. tension
1. The property of matter that causes an object to
resist changes in its state of motion is called:
A. friction
*B. inertia
C. the normal force
D. tension
2. If the net force on an object is increased, the
magnitude of its ______________ increases.
A. acceleration
B. velocity
C. both A and B
D. neither A nor B
2. If the net force on an object is increased, the
magnitude of its ______________ increases.
*A. acceleration
B. velocity
C. both A and B
D. neither A nor B
3. The SI unit for weight is the:
A. Joule
B. kilogram
C. Newton
D. pound
3. The SI unit for weight is the:
A. Joule
B. kilogram
*C. Newton
D. pound
4. 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
4. 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
B. 2 N [E]
C. 8 N [E]
D. It cannot be determined.
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
B. 2 N [E]
C. 8 N [E]
D. It cannot be determined.
6. If the distance between two objects is halved
the gravitational attraction between them is:
A. the same
B. doubled
C. halved
D. quadrupled
6. If the distance between two objects is halved
the gravitational attraction between them is:
A. the same
B. doubled
C. halved
*D. quadrupled
7. 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
7. 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
B. down
C. into the door
D. out of the door
8. A magnet is sliding down a fridge door. What
is the direction of the normal force acting on
the magnet?
A. up
B. down
C. into the door
*D. out of the door
9. 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
B. 10 N
C. 20 N
D. 30 N
9. 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
B. 10 N
*C. 20 N
D. 30 N
10. 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
B. less than
C. greater than
D. It cannot be determined.
10. 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
B. less than
C. greater than
D. It cannot be determined.
11. 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]
11. 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
B. 8 N [down] the book exerts on the table
C. 8 N [up] the book exerts on the Earth
D. There is no reaction force.
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
B. 8 N [down] the book exerts on the table
*C. 8 N [up] the book exerts on the Earth
D. There is no reaction force.
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
B. less than 4.0 N
C. 4.0 N
D. greater than 4.0 N
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
*B. less than 4.0 N
C. 4.0 N
D. greater than 4.0 N
14. 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
B. angled toward the front of the car
C. hanging straight down
D. It cannot be determined.
14. 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
B. angled toward the front of the car
*C. hanging straight down
D. It cannot be determined.
15. 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
15. 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
1. A sled is being pulled rightward across a
surface by a horizontal rope tied to it. Draw the
FBD for the sled.
FN
FA
Ff
Fg
2. If the rope is at an angle above the horizontal,
how will the other forces on the sled be
affected? Explain why.
2. If the rope is at an angle above the horizontal,
how will the other forces on the sled be
affected? Explain why.
Weight will not be affected.
Normal force will be decreased because the applied
force will have a vertical upward component.
Friction will be decreased because the normal force will
be decreased.
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.
The net force equal to the horizontal component of the
applied force minus the frictional force (vertical
forces cancel out).
You don’t know if the sled is speeding up or slowing
down because you don’t know which force is larger.
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?
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
Fnet ms g  F f
a

m
ms  mc
a
0.25 kg 9.8 sm   1.2 N
2
0.25 kg  0.40 kg
 1.923 sm2
or 1.9 sm2
and (b) the tension in the string between the cart
and the mass?
For the suspended mass :
Fnet  ms g  T
ms a  ms g  T  T  ms ( g  a )
T  (0.25 kg)(9.8 sm2  1.923 sm2 )
T  2.0 N
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 mk = 0.30. Find (a) the acceleration
of the box and (b) the distance travelled by the
box before stopping.
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 mk = 0.30. Find (a) the acceleration
of the box
Fnet F f mmg
a


 mg
m
m
m
a  0.30 9.8 sm2  2.94 sm2


or 2.9 sm2 [backwards]
and (b) the distance travelled by the box before
stopping.
a  2.94 sm2
v1  4.2 ms
v2  0 ms
d  ?
 v1
v2  v1  2ad  d 
for v2  0
2a
m 2
 4.2 s 
d 
 3.0 m
m
2  2.94 s 2
2
2
2


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.
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.
For Skater 2 :
Fnet FA  mmg
a

m
m
70.0 N  (0.10)(70.0 kg)(9.8 sm2 )
a
70.0 kg
a  0.020 sm2
and the direction would be [ East ]
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.
For Skater1 :
Fnet FA  mmg
a

m
m
70.0 N  (0.10)(50.0 kg)(9.8 sm2 )
a
50.0 kg
a  0.42 sm2
and the direction would be [West ]