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8th Grade
Forces and Motion
Study Guide www.njctl.org
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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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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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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?
A Average Speed B Instantaneous Speed
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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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SLIDE 3 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
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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
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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 490 m/s west B 10 m/s west C 490 m/s D 10 m/s
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SLIDE 4 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
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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
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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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SLIDE 5 11 Which of the following graphs depicts the
acceleration of a runner speeding up to pass someone. A B C
x
Y
Speed (m/s) Time (s) x
Y
Speed (m/s) Time (s)
x
Y
Speed (m/s) Time (s)
D
x
Y
Speed (m/s) Time (s)
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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?
A B C
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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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SLIDE 6 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
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15 What is the SI unit for force? A Pounds B Kilograms C Newtons
Slide 17 / 40 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
B
C
D + 30 balanced
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SLIDE 7 17 The force of gravitation between an object and a
planet is increased as they move away from each
True False
Slide 19 / 40 18 A 100 kg kid is on the moon, where g = 1.67 m/s2 .
What is the boy's weight? A 83.5 kg B 167 kg C 167 N D 29.9 N
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19 What is the net force acting on the object below?
7 N
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SLIDE 8 20 Is the object in equilibrium? Yes No
7 N
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21 What is the net force acting on the object below?
25 N
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22 Is the object in equilibrium? Yes No
25 N
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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?
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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?
Slide 26 / 40 25 Inertia is the reluctance any material object has
to change its state of motion. True False
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26 The law of inertia applies to:
A moving objects B nonmoving objects C both moving and nonmoving objects
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27 Which object has the greatest inertia? A Car B Tennis Ball C Freight Train
Slide 29 / 40 28 A ball will accelerate and increase its velocity
when it feels an unbalanced force. True False
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29 When the force acting on an object decreases,
the resulting acceleration will: A remain constant B increase C decrease
Slide 31 / 40 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
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31 You are riding your bicycle to the park to meet a few friends. As you ride, you apply a force of 40 N and accelerate at a rate of 0.4 m/s2 . What is the total mass of the bicycle and you? A 75 kg B 100 kg C 120 kg
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32 When you sit on a chair, the chair pushes back
with force equal to your weight. True False
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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.
Slide 35 / 40 34 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 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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36 What two factors does momentum depend on? A mass and volume B mass and acceleration C mass and velocity D mass and force
Slide 38 / 40 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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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?
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