Unit 3 mid term review
Modified True/False
Indicate whether the sentence or statement is true or false. If false, change the identified word or phrase to
make the sentence or statement true.
____
1. Unbalanced forces maintain motion at constant velocity. _________________________
____
2. The property of matter that resists a change in motion is called inertia.
_________________________
____
3. According to Newton’s second law of motion, force equals mass times weight.
_________________________
____
4. Friction depends on the types of surfaces involved and how hard the surfaces push together.
_________________________
____
5. The force of gravity decreases as the masses of objects increase. _________________________
____
6. When the only force acting on a falling object is air resistance, the object is said to be in free fall.
_________________________
____
7. Newton’s third law of motion explains that forces act alone. _________________________
____
8. A unit of momentum is kg•m/s. _________________________
____
9. A rocket will move upward as long as the thrust is greater than the pull of gravity.
_________________________
____ 10. The force that keeps a satellite in Earth orbit is always directed away from the center of Earth.
_________________________
Multiple Choice
Identify the letter of the choice that best completes the statement or answers the question.
____ 11. In physical science, a push or a pull is called a(n)
a. force.
b. acceleration.
c. inertia.
d. motion.
____ 12. When two equal forces act on the same object in opposite directions, the net force is
a. smaller than either force.
b. equal to each of the forces.
c. zero.
d. greater than either force.
____ 13. What happens when two forces act in the same direction?
a. They cancel each other out.
b. The stronger one prevails.
c. They add together.
d. Their sum divided by two is the total force.
____ 14. The tendency of an object to resist any change in its motion is known as
a. mass.
b. inertia.
____ 15.
____ 16.
____ 17.
____ 18.
____ 19.
____ 20.
____ 21.
____ 22.
____ 23.
____ 24.
c. force.
d. balance.
The amount of matter in an object is called its
a. weight.
b. mass.
c. force.
d. balance.
The greater the mass of an object,
a. the easier the object starts moving.
b. the greater its inertia.
c. the more balanced it is.
d. the more space it takes up.
Force equals mass times
a. speed.
b. motion.
c. acceleration.
d. inertia.
One way to increase acceleration is by
a. increasing mass.
b. decreasing mass.
c. decreasing force.
d. increasing both force and mass proportionally.
The force that one surface exerts on another when the two rub against each other is called
a. friction.
b. acceleration.
c. inertia.
d. gravity.
Which of the following is an example of increasing friction intentionally?
a. waxing skis
b. adding grease to gears on a bike
c. throwing sand on an icy driveway
d. oiling a squeaky door
Which of the following is an example of rolling friction?
a. your shoes on a sidewalk as you walk
b. bike tires on the road as you ride
c. a boat on the water as it sails
d. two hands rubbing together
When the only force acting on a falling object is gravity, the object is said to be
a. stationary.
b. decelerating.
c. in free fall.
d. a projectile.
The force that pulls falling objects toward Earth is called
a. gravity.
b. free fall.
c. acceleration.
d. air resistance.
Air resistance is a type of
a. motion.
____ 25.
____ 26.
____ 27.
____ 28.
____ 29.
____ 30.
____ 31.
____ 32.
____ 33.
b. acceleration.
c. velocity.
d. friction.
If you were on the moon, your weight would be roughly what fraction of your weight on Earth?
a. one third
b. one fourth
c. one fifth
d. one sixth
The force of gravity on a person or object at the surface of a planet is known as
a. mass.
b. inertia.
c. air resistance.
d. weight.
Weight equals mass times
a. force due to balanced forces.
b. acceleration due to gravity.
c. inertia due to force.
d. air resistance.
The law of universal gravitation states that any two objects in the universe, without exception,
a. attract each other.
b. repel each other.
c. combine to provide a balanced force.
d. create friction.
Objects falling through air experience a type of friction called
a. terminal velocity.
b. air resistance.
c. inertia.
d. rolling friction.
According to Newton’s third law of motion, when a hammer strikes and exerts force on a nail, the
nail
a. creates a friction with the hammer.
b. disappears into the wood.
c. exerts an equal force back on the hammer.
d. moves at a constant speed.
Two figure skaters who push off of each other will move at the same speed if
a. they push with the same force.
b. the ice does not cause any friction.
c. there is no air resistance.
d. they have the same mass.
Forces can be added together only if they are
a. acting on the same object.
b. balanced forces.
c. unaffected by gravity.
d. substantial.
The product of an object’s mass and velocity is called its
a. inertia.
b. momentum.
c. acceleration.
d. force.
____ 34. The momentum of an object is in the same direction as its
a. force.
b. acceleration.
c. velocity.
d. inertia.
____ 35. How can you increase the momentum of an object?
a. by decreasing its velocity
b. by increasing its mass
c. by increasing its friction
d. by decreasing its acceleration
____ 36. According to the law of conservation of momentum, when two objects collide in the absence of
friction,
a. velocity decreases.
b. velocity increases.
c. momentum is not lost.
d. only the object with the larger mass continues on.
____ 37. Which law can explain how gases released from burning fuel in a rocket produce thrust?
a. Newton’s first law of motion
b. Newton’s second law of motion
c. Newton’s third law of motion
d. the law of conservation of momentum
____ 38. What is required for a rocket to lift off into space?
a. thrust that is greater than Earth’s gravity
b. mass that is greater than Earth’s mass
c. very little air resistance
d. more velocity than friction
____ 39. An object that travels around another object in space is called a
a. projectile.
b. rocket.
c. mass.
d. satellite.
____ 40. Any force that causes an object to move in a circle is called a(n)
a. balanced force.
b. unbalanced force.
c. gravitational force.
d. centripetal force.
Completion
Complete each sentence or statement.
41. The overall force on an object after all the forces are added together is called the
____________________ force.
42. Unbalanced forces acting on an object produce ____________________ motion.
43. A measure of an object’s ____________________ is a measure of the object’s inertia.
44. One ____________________ is the force required to accelerate 1 kilogram of mass at 1 meter per
second per second.
45. A person traveling in a car that stops suddenly keeps moving forward because of
____________________.
46. Friction acts in a direction ____________________ to an object’s direction of motion.
47. Wet pavement is more slippery than dry pavement because the force needed to overcome
____________________ friction is less than the force needed to overcome sliding friction.
48. The downward force acting on an object in free fall is the force of ____________________.
49. A(n) ____________________ is an object that is thrown.
50. When _________________________ equals the force of gravity on a falling object, the object
reaches terminal velocity.
51. The metric unit that is most often used to describe weight is the ____________________.
52. The force of gravity between you and Earth is greater than the force of gravity between you and a
car because Earth has more ____________________ than the car.
53. As the distance between two objects decreases, the gravitational force between them
____________________.
54. According to Newton’s third law of motion, the strength of a reaction force is
_________________________ the strength of the action force.
55. If the action force of a bat striking a ball accelerates the ball in one direction, the reaction force
accelerates the bat in the ____________________ direction.
56. The momentum of an object is in the same ____________________ as its velocity.
57. The momentum of a roller skater is not conserved because ____________________ acts on the
skates.
58. During lift-off, the thrust on a rocket is directed ____________________.
59. The moon is a natural ____________________ of Earth.
60. The force of gravity is responsible for continuously changing the ____________________ in
which a satellite moves.
Unit 3 mid term review
Answer Section
MODIFIED TRUE/FALSE
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
F, Balanced
T
F, acceleration
T
F, increases
F, gravity
F, in pairs
T
T
F, toward
MULTIPLE CHOICE
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
26.
27.
28.
29.
30.
31.
32.
33.
34.
35.
36.
37.
38.
A
C
C
B
B
B
C
B
A
C
B
C
A
D
D
D
B
A
B
C
D
A
B
C
B
C
C
A
39. D
40. D
COMPLETION
41.
42.
43.
44.
45.
46.
47.
48.
49.
50.
51.
52.
53.
54.
55.
56.
57.
58.
59.
60.
net
accelerated
mass
newton
inertia
opposite
fluid
gravity
projectile
air resistance
newton
mass
increases
equal to
opposite
direction
friction
upward
satellite
direction