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```Name:
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Chapter 3 Honors Physical Science Study Guide
Modified True / False
1. The momentum of an object is the sum of its mass and its velocity. ____________________
ANSWER: False - product
2. A baseball hurled by a powerful pitcher has greater acceleration than one lobbed gently. _________________________
3. The acceleration of an object depends on its volume as well as the force exerted on it. _________________________
ANSWER: False - mass
4. a = F /v _________________________
ANSWER: False - m
5. If the net force on a moving object is 0, it will continue to move in a curve with a constant speed.
_________________________
ANSWER: False - in a straight line
6. The amount of friction between two surfaces depends on the kinds of surfaces and the force pressing the surfaces
together. _________________________
Multiple Choice
7. _____ is the force that opposes the sliding motion of two surfaces that are touching each other.
a. Friction
b. Inertia
c. Static
d. Gravity
8. _____ is a force that opposes the motion of objects that move through the air.
a. Air resistance
b. Gravity
c. Static friction
d. Rolling friction
9. Gravity is always _____.
a. attractive
b. repulsive
c. both a and be
d. nether a nor b
10. Acceleration toward the center of a curved path is called _____acceleration.
a. mass
b. weight
c. volume
d. charge
11. The sum of all the forces acting on an object is called the _____ force.
a. net
b. gravitational
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c. final
d. inertial
12. The upward force exerted on an object falling through air is _____.
a. terminal velocity
b. momentum
c. air resistance
d. weightless
13. When an object moves in a circular path, it accelerates toward the center of the circle as a result of _____.
a. terminal velocity
b. momentum
c. centripetal force
d. friction
14. The statement “to every reaction there is an equal and opposite reaction” is _____.
a. the law of conservation of momentum
b. Newton’s first law of motion
c. Newton’s second law of motion
d. Newton’s third law of motion
15. The product of mass and velocity gives a quantity known as _____.
a. momentum
b. friction
c. inertia
d. velocity
16. When a rocket lifts off, its upward momentum is matched by the downward momentum of _____.
a. nothing
b. hot gases expelled by the rocket
c. air pushed out the way by the rocket
d. the launch pad
17. An object that is in free fall seems to be _____.
a. weightless
b. slowed by air resistance
c. speeded up by air resistance
d. not moving
18. The relationship among mass, force, and acceleration is explained by _____.
a. Newton’s first law of motion
b. Newton’s second law of motion
c. Newton’s third law of motion
d. the conservation of momentum
19. When two objects collide, their momentum after the collision is explained by _____.
a. Newton’s first law of motion
b. Newton’s second law of motion
c. Newton’s third law of motion
d. the conservation of momentum
20. A feather will fall through the air more slowly than a brick because of _____.
a. gravity
b. air resistance
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c. terminal velocity
d. momentum
21. In the absence of air, a penny and a feather dropped from the same height will _____.
a. fall at different rates
b. float
c. fall at the same rates
d. not have momentum
22. The amount of gravitational force between objects depends on their _____.
a. frictional forces
b. speed and direction
c. inertia
d. masses and the distances between them
23. When a car traveling at 50 km/h collides head-on with something solid, the car stops within approximately _____.
a. 10 s
b. 2 s
c. 100 s
d. 0.1 s
24. An object at terminal velocity has an acceleration of _____.
a. zero
b. 1 g
c. 9.8 m/s
d. 98 m/s
25. Acceleration due to gravity is _____.
a. 98 m/s
b. 9.8 m/s
c. 9.8 m/s
d. 0.98 m/s
26. If a 300-N action force is exerted to the right, the reaction force will be _____.
a. 300 N to the right
b. 600 N to the right
c. 300 N to the left
d. 600 N to the left
27. When a force is exerted on an object, an equal and opposite force is exerted by the object. These forces are referred to
as _____.
a. centripetal forces
b. friction forces
c. gravitational forces
d. action-reaction forces
28. A real car moving at 10 km/h has more momentum than a toy car moving at the same rate because _____.
a. its mass is greater
b. its mass is less
c. it moves faster
d. of friction
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29. An object attached to a string that is being swung in a clockwise circular path is shown. Assume the string breaks at
point A. In which direction will the object be traveling an instant later?
a. arrow up
b. arrow down
c. arrow up/diagonal
d. arrow to right
30. An object attached to a string that is being swung in a clockwise circular path is shown. Assume the string breaks at
point A. What kind of path will the object follow after the string breaks?
a. a straight line
b. the same curve as when attached to the string
c. straight to the ground
d. cannot be determined
31. According to Newton’s second law of motion, _____.
a. F = mv
b. F = ma
c. F = pv
d. F = PA
32. Friction between the tire of a moving car and the dry pavement is _____ friction.
a. static
b. rolling
c. sliding
d. riding
33. Gravity is one of _____ basic forces.
a. two
b. three
c. four
d. five
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34. A car rounding a curve is subject to _____ force.
a. rolling
b. static
c. centripetal
d. gravitational
35. Astronauts aboard the International Space Station are _____ because they are in orbit around the Earth.
a. at terminal velocity
b. motionless
c. frictionless
d. weightless
Completion
36. ____________________ is the force that opposes the sliding motion of two surfaces that are touching each other.
37. ____________________ is a force that opposes the motion of objects that move through the air.
38. Gravity is always ____________________.
39. The gravitational force exerted on an object is called the object’s ____________________.
40. Acceleration toward the center of a curved path is called ____________________ acceleration.
41. The sum of all the forces acting on an object is known as the ____________________ force.
42. The momentum of an object is the ____________________ of its mass and its velocity.
43. A baseball hurled by a powerful pitcher has greater ____________________ than one lobbed gently.
44. The acceleration of an object depends on its ____________________ as well as the force exerted on it.
45. a = F / ____________________.
46. If the net force on a moving object is ____________________, it will continue to move in a straight line with a
constant speed.
47. The amount of friction between two surfaces depends on ____________________ and the force pressing the surfaces
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together.
ANSWER: the kinds of surface
48. To keep a sliding object moving, you must continually overcome ____________________.
49. Air resistance acts in ____________________ to the motion of an object through air.
ANSWER: the opposite direction
50. As an object falls faster, the force of air resistance ____________________.
51. At terminal velocity, the acceleration of an object is ____________________.
52. Terminal velocity depends on the size, shape, and ____________________ of a falling object.
53. There are ____________________ basic forces in the universe.
54. What does Newton’s second law of motion state?
ANSWER: Newton’s second law of motion states that the acceleration of an object is in the same direction as the net force
on the object.
55. What does Newton’s third law of motion state?
ANSWER: Newton’s third law of motion states that when one object exerts a force on another object, the second object
exerts a force on the first object that is equal in strength but opposite in direction.
56. Evaluate this statement: “When I push on my refrigerator, there is a force acting on it that wasn’t there before. That
means it should be experiencing an unbalanced force and begin to move. Why doesn’t it?” How would you answer?
ANSWER: The force you are applying to the refrigerator is being canceled out by an equal and opposite force: static
friction. If you could push hard enough to overcome this force, the net force on the refrigerator would not be 0,
and the refrigerator would begin to move.
57. Evaluate this statement: “We pushed and pushed on the motionless couch until sliding friction was overcome, and it
started moving.”
ANSWER: This is incorrect. Static friction was overcome at the moment the couch began moving. Sliding friction must
be continually overcome to keep it in motion.
58. Evaluate this statement: “Once sliding friction has been overcome, an object will remain in motion without a force
being applied.”
ANSWER: This is incorrect. Sliding friction must be continually overcome in order to keep a sliding object in motion.
59. How could you use two equal-sized pieces of paper to show how air resistance affects objects of different shapes?
ANSWER: Answer will vary, but should reflect the idea that changing shapes of one or both pieces of paper will cause the
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amount of air resistance affecting the sheets of paper to differ.
60. “If gravity causes everything to fall with the same acceleration,” a friend asks, “then why does a crumpled piece of
paper fall faster than an uncrumpled one?” How would you answer?
ANSWER: The difference in acceleration between the crumpled paper and the uncrumpled paper is not due to gravity but
to air resistance. The uncrumpled paper, having greater surface area, is slowed more by the air.
61. “When a car turns,” a friend states, “the less friction the better, because friction just slows you down.” How would you
respond to your friend’s claim?
ANSWER: This is incorrect. In order to change directions, a car requires friction between the tires and the road. If friction
is insufficient, the car will continue in a straight path and drive off the road.
62. Evaluate this statement: “The object is in motion in a straight line, and it is moving with a constant speed. That must
mean that no forces are acting on it.”
ANSWER: This is incorrect. It is possible that forces are acting on it, as long as the net force acting on it is 0.
63. Evaluate this statement: “As long as the baseball I hit is moving upward, there is no air resistance. Air resistance only
slows down when it is falling downward again.”
ANSWER: This is incorrect. Air resistance acts on the ball the entire time it is in motion through the air and acts opposite
to its direction of motion.
64. How can a rocket work even in deep space where there is nothing to push off of?
ANSWER: A rocket does not work by pushing off the ground. Instead, it causes gases to be expelled out the back of the
rocket, which exerts a force on the rocket and pushes it forward.
65. Study the diagram. Then answer the questions that follow. An object attached to a string that is being swung in a
clockwise circular path is shown. Assume the string breaks at point A. In which direction will the object be traveling an
instant later? What kind of path will the object follow after the string breaks? Before the string breaks, in what direction is
the centripetal force acting on the object pointing?
d; a straight line; toward the center of the circle
66. In an events chain concept map showing what happens when a bowling ball strikes the pins. How does the momentum
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of the bowling ball change at the time of impact? What happens to the momentum of the pins at impact?
ANSWER: The ball loses momentum. The pins gain momentum equal to that lost by the ball.
67. What is the force of an object with a mass of 12 kg and an acceleration of 4 m/s ?
ANSWER: F = ma = 12 kg × 4 m/s = 48 kg·m/s
F = 48 N
68. Calculate the acceleration of a 25-kg object that is moved with a force of 300 N.
ANSWER: F = ma
300 N = 25 kg × a
300 kg·m/s /25 kg = a
a = 12 m/s
69. What is the mass of an object that is accelerating at 15 m/s when a force of 3000 N is exerted?
ANSWER: F = ma
3000 N = m × 15 m/s
3000 kg·m/s /15 m/s = m
m = 200 kg
70. Complete the table below by calculating the missing values. Use the information in the table to answer the following
questions.
Object
A
B
C
D
Mass
10 kg
Velocity
25 m/s
25 m/s
25 kg
25 m/s
Momentum
300 kg x m/s
300 kg x m/s
500 kg x m/s
a. Which object has the greatest momentum?
b. Which object has the lest momentum?
c. How does the momentum of object B compare with the momentum of object C?
d. Why is the momentum for object B greater than the momentum for object A?
e. What factor causes object D to have a greater momentum than object C?
ANSWER: A. 250 kg·m/s
B. 12 kg
C. 12 m/s
D. 20 kg
a. D
b. A
c. They have the same momentum
d. Object B has a greater mass than object A.
e. Object D has a greater velocity than object C.
Essay
71. Contract static friction, sliding friction, and rolling friction.
ANSWER: Static friction is the frictional force that prevents two surfaces from sliding past each other. Sliding friction is
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the force that opposes the motion of two surfaces sliding past each other. Rolling friction is the frictional force
between a rolling object and the surface on which it rolls.
72. Two object that have the same mass are dropped from the top of a 20-m high building. One object is larger and flatter
than the other object. Explain why the larger, flatter object hits the ground last.
ANSWER: The amount of air resistance is greater on the larger, flatter object. Since gravity accelerates all samples of
matter at the same rate, the air resistance is what slows the larger object’s fall. The greater the amount of air
resistance on the larger object pushes up on the object as gravity pulls it down.
73. What are two examples of gravitational force in our daily life?
ANSWER: Answers will vary but may include such activities as jumping rope, running, or throwing a ball.
74. How is mass different from weight?
ANSWER: Mass is a measure of the amount of matter in an object; it is measured in grams and kilograms. Weight is a
measure of the force of gravity on an object. It is measured in units called newtons.