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8th Grade
Forces and Motion
Study Guide
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1
A snail travels 10 m in 3000 seconds. What is the
snail's average speed?
A
60000 m/s
B
0.02 m/s
C
600 m/s
D
0.003 m/s
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2
2
A
60000 m/s
B
0.02 m/s
C
600 m/s
D
0.003 m/s
Answer
A snail travels 10 m in 3000 seconds. What is the
snail's average speed?
D
A blimp travels at 3 m/s for 1000 s. What distance
does the blimp cover in that time?
A
500 m/s
B
3000 m
C
4500 m/s
D
500 m
A blimp travels at 3 m/s for 1000 s. What distance
does the blimp cover in that time?
A
500 m/s
B
3000 m
C
4500 m/s
D
500 m
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Answer
1
B
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3
When your teacher times your mile run at 8.2
minutes, that means your speed was 0.12 mi/min.
Was this your average speed or your instantaneous
speed?
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A Average Speed
B Instantaneous Speed
3
When your teacher times your mile run at 8.2
minutes, that means your speed was 0.12 mi/min.
Was this your average speed or your instantaneous
speed?
Answer
A Average Speed
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avg speed =
B Instantaneous Speed
8.2mi/min
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4
Does a speedometer measure the average speed or
the instantaneous speed?
A Average Speed
B Instantaneous Speed
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4
Does a speedometer measure the average speed or
the instantaneous speed?
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B Instantaneous Speed
Answer
A Average Speed
Instantaneous
Speed
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5 A swordfish travels for two hours. The first hour he
covers 110 kilometers, and the second hour he
covers 110 kilometers. What is the average speed of
the swordfish?
A
55 km/h
B
84 km/h
C
110 km/h
D
194 km/h
Hint: Remember
that average speed
is total distance
travelled divided by
total time
5 A swordfish travels for two hours. The first hour he
covers 110 kilometers, and the second hour he
covers 110 kilometers. What is the average speed of
the swordfish?
55 km/h
B
84 km/h
C
110 km/h
D
194 km/h
Hint: Remember
that average speed
is total distance
travelled divided by
total time
Answer
A
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C
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6 A dog walks outside to go the bathroom every day. If
she walks outside at a speed of 3 meters per second
and walks 150 meters before she uses the bathroom,
how long does it take her?
A
50 seconds
B
2 minutes
C
188 seconds
D
90 seconds
A
50 seconds
B
2 minutes
C
188 seconds
D
90 seconds
Answer
6 A dog walks outside to go the bathroom every day. If
she walks outside at a speed of 3 meters per second
and walks 150 meters before she uses the bathroom,
how long does it take her?
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Slide 8 (Answer) / 40
A
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7 Carlos and Gina are riding on their horses to go into
town. They travel 140 meters in 14 seconds going
west. What is their velocity?
A
B
C
D
490 m/s west
10 m/s west
490 m/s
10 m/s
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7 Carlos and Gina are riding on their horses to go into
town. They travel 140 meters in 14 seconds going
west. What is their velocity?
490 m/s west
10 m/s west
490 m/s
10 m/s
Answer
A
B
C
D
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B
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8 A car travels 200 km/h west for 2 hours. The car then
travels 150 km/h east for one hour. What is the car's
position relative to its starting position?
A
50 km west
B
150 km west
C
250 km west
D
50 km east
A
50 km west
B
150 km west
C
250 km west
D
50 km east
Answer
8 A car travels 200 km/h west for 2 hours. The car then
travels 150 km/h east for one hour. What is the car's
position relative to its starting position?
C
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9
A nitro-methane powered top fuel dragster
launches from rest to race against an opponent.
Why did the car accelerate?
A
increased speed
B
decreased speed
C
changed direction
A nitro-methane powered top fuel dragster
launches from rest to race against an opponent.
Why did the car accelerate?
A
increased speed
B
decreased speed
C
changed direction
Answer
9
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Slide 11 (Answer) / 40
A
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10
A driver hits the brakes to slow down at an
intersection. As the car's speed is decreasing it has
A positive acceleration
B negative acceleration
C no acceleration
D more information is needed
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10
A driver hits the brakes to slow down at an
intersection. As the car's speed is decreasing it has
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A positive acceleration
B
Answer
B negative acceleration
C no acceleration
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D more information is needed
D
Time (s)
x
Y
Time (s)
Speed (m/s)
Time (s)
Y
Answer
C
x
D
Time (s)
x
Y
Speed (m/s)
Speed (m/s)
Time (s)
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x
x
Which of the following graphs depicts the
acceleration of a runner speeding up to pass
someone.
Y
Y
B
A
Speed (m/s)
11
Time (s)
Y
Speed (m/s)
C
x
Speed (m/s)
Time (s)
Speed (m/s)
Which of the following graphs depicts the
acceleration of a runner speeding up to pass
someone.
Y
Y
B
A
Speed (m/s)
11
x
C
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Time (s)
x
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12 Which of the following speed vs time graphs
corresponds to the position vs time graph shown in
the graph below?
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A
B
C
12 Which of the following speed vs time graphs
corresponds to the position vs time graph shown in
the graph below?
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Answer
A
A
B
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C
13 A ball is traveling down a hill at 4 m/s. If the ball
increases in speed to 8 m/s in 4 seconds, what is the
acceleration of the ball?
A
4 m/s
B
4 m/s/s
C
1 m/s
D
1 m/s/s
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A
4 m/s
B
4 m/s/s
C
1 m/s
D
1 m/s/s
Answer
13 A ball is traveling down a hill at 4 m/s. If the ball
increases in speed to 8 m/s in 4 seconds, what is the
acceleration of the ball?
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D
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14 Forces are all around us. Which of the following
do you think are examples of forces? (choose all
that apply)
A
Gravity
B
Friction
C
Muscles
D
Wind
A
Gravity
B
Friction
C
Muscles
D
Wind
Answer
14 Forces are all around us. Which of the following
do you think are examples of forces? (choose all
that apply)
A&B
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15 What is the SI unit for force?
A Pounds
B Kilograms
C Newtons
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15 What is the SI unit for force?
B Kilograms
C Newtons
Answer
A Pounds
C
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16
A +20 N force acts on a car and at the same time,
a -30 N force acts on the car. What is the net
force acting on the car and is it balanced?
A
-30 N unbalanced
B
-10 N unbalanced
C
-10 N balanced
D
+ 30 balanced
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A +20 N force acts on a car and at the same time,
a -30 N force acts on the car. What is the net
force acting on the car and is it balanced?
A
-30 N unbalanced
B
-10 N unbalanced
C
-10 N balanced
Answer
16
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B
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D
17
+ 30 balanced
The force of gravitation between an object and a
planet is increased as they move away from each
other:
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True
False
The force of gravitation between an object and a
planet is increased as they move away from each
other:
True
False
Answer
17
False
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18
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A 100 kg kid is on the moon, where g = 1.67 m/s .
What is the boy's weight?
2
A 83.5 kg
B 167 kg
C 167 N
D 29.9 N
18
Slide 20 (Answer) / 40
A 100 kg kid is on the moon, where g = 1.67 m/s .
What is the boy's weight?
2
A 83.5 kg
C 167 N
Answer
B 167 kg
C
D 29.9 N
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19 What is the net force acting on the object below?
-10 N
7N
-8 N
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19 What is the net force acting on the object below?
7N
Answer
-10 N
-11 N
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-8 N
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20 Is the object in equilibrium?
Yes
No
-10 N
7N
-8 N
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20 Is the object in equilibrium?
Yes
No
7N
Answer
-10 N
No
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-8 N
21 What is the net force acting on the object below?
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-10 N
25 N
-15N
21 What is the net force acting on the object below?
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25 N
Answer
-10 N
0N
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-15N
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22 Is the object in equilibrium?
Yes
No
-10 N
25 N
-15N
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22 Is the object in equilibrium?
Yes
No
25 N
Answer
-10 N
Yes
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-15N
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23 Acceleration due to gravity on Jupiter is 26.1 m/s2 .
How much would a 25 kg person weigh on Jupiter?
Slide 25 (Answer) / 40
Answer
23 Acceleration due to gravity on Jupiter is 26.1 m/s2 .
How much would a 25 kg person weigh on Jupiter?
653 N
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24 Acceleration due to gravity on Earth's Moon is
1.67 m/s2 . How much would a 113 kg person
weigh on Earth's Moon?
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24 Acceleration due to gravity on Earth's Moon is
Answer
1.67 m/s2 . How much would a 113 kg person
weigh on Earth's Moon?
189 N
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25
Inertia is the reluctance any material object has
to change its state of motion.
True
False
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Inertia is the reluctance any material object has
to change its state of motion.
True
False
Answer
25
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True
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26
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The law of inertia applies to:
A
moving objects
B
nonmoving objects
C
both moving and nonmoving objects
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The law of inertia applies to:
A
moving objects
B
nonmoving objects
C
both moving and nonmoving objects
Answer
26
C
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27 Which object has the greatest inertia?
A
Car
B
Tennis Ball
C
Freight Train
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28
A
Car
B
Tennis Ball
C
Freight Train
Answer
27 Which object has the greatest inertia?
C
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A ball will accelerate and increase its velocity
when it feels an unbalanced force.
True
False
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28
A ball will accelerate and increase its velocity
when it feels an unbalanced force.
Slide 30 (Answer) / 40
False
Answer
True
True
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29
When the force acting on an object decreases,
the resulting acceleration will:
A
remain constant
B
increase
C
decrease
When the force acting on an object decreases,
the resulting acceleration will:
A
remain constant
B
increase
C
decrease
Answer
29
C
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30
When an object's mass is decreased but the
applied force stays the same, the resulting
acceleration will:
A
remain constant
B
increase
C
decrease
When an object's mass is decreased but the
applied force stays the same, the resulting
acceleration will:
A
remain constant
B
increase
C
decrease
Answer
30
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force of 40 N and accelerate at a rate of 0.4 m/s2 .
What is the total mass of the bicycle and you?
75 kg
B
100 kg
C
120 kg
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B
31 You are riding your bicycle to the park to
meet a few friends. As you ride, you apply a
A
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31 You are riding your bicycle to the park to
meet a few friends. As you ride, you apply a
Slide 33 (Answer) / 40
Answer
force of 40 N and accelerate at a rate of 0.4 m/s2 .
What is the total mass of the bicycle and you?
32
A
75 kg
B
100 kg
C
120 kg
B
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When you sit on a chair, the chair pushes back
with force equal to your weight.
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True
False
When you sit on a chair, the chair pushes back
with force equal to your weight.
True
False
Answer
32
True
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33 Which of the following statements pertains to the
third law of motion?
A
Action and Reaction pairs always act on
the same object.
B
Mass is indirectly proportional to acceleration.
C
An object at rest will remain at rest unless
acted on by an unbalanced force.
D
If a force occurs, action reaction forces are
present.
33 Which of the following statements pertains to the
third law of motion?
34
Action and Reaction pairs always act on
the same object.
B
Mass is indirectly proportional to acceleration.
C
An object at rest will remain at rest unless
acted on by an unbalanced force.
D
If a force occurs, action reaction forces are
present.
Answer
A
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Slide 35 (Answer) / 40
D
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How can a small toy have the same momentum as
a large car?
A
toy has large speed
B
both car and toy are at rest
C
toy has no mass
D
A&B
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35
35
How can a small toy have the same momentum as
a large car?
toy has large speed
B
both car and toy are at rest
C
toy has no mass
D
A&B
Answer
A
D
If a 3 kg toy truck is moving at 4 m/s, what is the
toy's momentum?
A
3 m/s
B
2 kgm/s
C
12 kgm/s
D
12 m/s
If a 3 kg toy truck is moving at 4 m/s, what is the
toy's momentum?
A
3 m/s
B
2 kgm/s
C
12 kgm/s
D
12 m/s
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Answer
34
C
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Slide 37 (Answer) / 40
36 What two factors does momentum depend on?
A
mass and volume
B
mass and acceleration
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C mass and velocity
D mass and force
A
mass and volume
B
mass and acceleration
C mass and velocity
D mass and force
Answer
36 What two factors does momentum depend on?
Slide 38 (Answer) / 40
C
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37
The law of conservation of momentum states that
the total momentum after a collision increases
from its value before the collision.
True
False
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37
The law of conservation of momentum states that
the total momentum after a collision increases
from its value before the collision.
Slide 39 (Answer) / 40
Answer
True
False
False
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38 According to Newton's 3rd law, action reaction
pairs are equal and opposite to each other. Why do
these paired forces sometimes cause different
motions if they are equal?
Answer
38 According to Newton's 3rd law, action reaction
pairs are equal and opposite to each other. Why do
these paired forces sometimes cause different
motions if they are equal?
because they
act on different
objects
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Slide 40 (Answer) / 40