Download Chapter 3 Test Review Key Vocabulary: Set 1: Set 2:

Chapter 3 Test Review Key
Vocabulary:
Set 1: 1.E 2. C 3.A 4.B 5.F
Set 2: 1.B 2.F 3.D 4.C 5. A
Set 3: 1.B 2.F 3. D 4.E 5.C
Set 4: 1.D 2.A 3.B 4. C 5.F
1. Define the term force, and give some examples of forces.
A force is any push or pull that has the ability to change the motion of an object.
2. Describe how Newton’s First Law (the law of inertia) applies to wearing seatbelts in a car.
Since objects in motion tend to stay in motion, when a car is stopped suddenly or speeds up suddenly, your
body tends to resist the change in motion and the seatbelts help keep you in place.
3. Which has more inertia, a 1-kilogram baseball or a 10-kilogram bowling ball?
The 10 kg bowling ball has more inertia.
4. Which two units combine to make a Newton?
A Newton is equal to a kg x m/s2
5. According to Newton’s Second Law, what will happen to the acceleration of an object when:
a. The mass is increased: The acceleration will decrease
b. The Force is increased: The acceleration will increase
6. Zoo keepers lift a cage that holds a lion. The total mass of the lion and cage is 175 kg and the acceleration of the
lion and cage in 0.657 m/s2.What force is needed to produce this acceleration of the lion and the cage?
F = ma = (175kg) (0.657m/s2) = 114.975 N
7. A car pulled by a tow truck has an acceleration of 2.0 m/s2. What is the mass of the car if the net force on the car
is 3,000 N east?
m=F/a = (3,000 N) / (2.0 m/s2) = 1500 kg
8. If a helicopter’s mass is 4,500 kg and the net force on it is 18,000 N upward, what is its acceleration?
a=F/m = (18,000N) / (4,500 kg) = 4 m/s2
9. Explain the difference between mass and weight.
Mass is a fundamental property that describes the amount of matter in an object, while weight is the effect of
gravity on the mass. Mass will never change, however, weight will when the gravity changes.
10. On the surface of the Earth, what is the acceleration due to gravity?
The acceleration due to gravity on Earth is 9.8 m/s2
11. A wrestler weighs in for his first match on the moon. Will the athlete weigh more or less on the moon than he
does on Earth? Explain your answer using the terms weight, mass, and gravity.
Although the wrestler’s mass would not change, the wrestler would weigh less on the moon, because the gravity
on the moon is less than the gravity on Earth.
12. What is the weight of a 2.25 kg book bag on the Earth?
W = mg = (2.25 kg)(9.8 m/s2) = 22.05 N
13. If that same textbook weighs 14.625 N on another planet, what is the acceleration due to gravity there?
(Remember mass is still the same)
g = W/m = (14.625 N) /(2.25 kg) = 6.5 m/s2
14. The idea that any two objects with mass are exerting a force on each other is called what?
The Law of Universal Gravitation.
15. What happens to the gravitational force between two objects if:
a. The masses do not change but the distance between them increases? The gravity decreases
b. The distance does not change but one increases in mass? The gravity increases
16. Explain the effect that viscosity has on friction?
The more viscous a liquid is, the more resistance there will be on an object moving through the liquid.
17. Explain the effect that uneven surfaces have on friction?
The more uneven a surface is, the more resistance there will be to an object moving on it. The smoother the
surface, the less resistance.
18. Using a specific type of friction, explain how a skydiver opening her parachute slows her down.
When the skydiver opens her parachute, she is increasing the amount of air friction action on her, and that
resistance that the air is exerting on her allows her to fall slower.
19. During gym, two teams are playing Tug of War. The pink team on the left side of the rope has three players –
one who pulls with 2 N of force and two who pull with 1 N of force. The blue team, on the ride side of the rope
also has 3 players, two who pull with 2 N of force and one who pulls with 1 N of force. Sketch the scenario. What
is the net force on the rope?
20. A 12 kg computer is at rest on a desk in an office. Show the forces acting on the object. Calculate its weight and
its normal force. What is the net force on the object? What do we call this?
21. Fill in the blanks in the following statements:
a.
Forces always occur in pairs
b.
Each force in an action-reaction pair of forces is equal magnitude
c. Each force in an action-reaction pair of forces is opposite in direction
22. Describe the action reaction forces of a swimmer swimming the length of a pool.
Action: The swimmer pulls the water behind her.
Reaction: The water pushes the swimmer forward
23. Describe the action reaction forces of a textbook at rest on a desk.
Action: The textbook pushes down on the desk with its weight.
Reaction: The desk pushes on the textbook with its normal force.