Download Chapter Review

Name
Class
Date
Skills Worksheet
Chapter Review
USING VOCABULARY
______ 1. Academic Vocabulary In the sentence “Gravity has an important role in
maintaining the shape of the solar system,” what does the word
role mean?
a. a part played by an actor
b. a function
c. a socially expected behavior pattern
d. a character assigned or taken on
Complete each of the following sentences by choosing the correct term from the
word bank.
gravity
terminal velocity
projectile motion
mass
2. An object in motion has
inertia
weight
, so it tends to stay
in motion.
3. An object is falling at its
if it falls at a constant
velocity.
4.
is a measure of the gravitational force on an object.
UNDERSTANDING CONCEPTS
Multiple Choice
______ 5. The gravitational force between 1 kg of lead and Earth is the _____
gravitational force between 1 kg of marshmallows and Earth.
a. greater than
b. less than
c. the same as
d. None of the above
______ 6. Newton’s first law of motion applies to
a. moving objects.
b. objects that are not moving.
c. objects that are accelerating.
d. Both (a) and (b)
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Holt California Physical Science
42
Forces and Motion
Name
Class
Date
Chapter Review continued
______ 7. To accelerate two objects at the same rate, the force used to push the
object that has more mass should be
a. smaller than the force used to push the object that has less mass.
b. larger than the force used to push the object that has less mass.
c. the same as the force used to push the object that has less mass.
d. equal to the object’s weight.
Short Answer
8. Identifying Give an example of an object that is in free fall.
9. Summarizing Describe how the cumulative effect of gravity and air resistance
is related to an object’s terminal velocity.
10. Describing Explain why friction changes the velocity of objects and why
friction can make observing Newton’s first law of motion difficult.
11. Concluding What would happen to the magnitude of the gravitational force
between the sun and Earth if Earth were placed in Pluto’s orbit?
12. Analyzing Explain why action and reaction forces do not cancel out, even
though they have equal magnitudes and act in opposite directions.
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Holt California Physical Science
43
Forces and Motion
Name
Class
Date
Chapter Review continued
INTERPRETING GRAPHICS
Use the image below to answer the next two questions.
13. Identifying The arrows in the image indicate two separate forces that are
acting in the upward and downward directions on the static light bulb.
Identify these two forces.
14. Justifying Are the forces on the light bulb balanced or unbalanced? Explain
your answer by considering the motion of the light bulb.
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Holt California Physical Science
44
Forces and Motion
Name
Class
Date
Chapter Review continued
INTERPRETING GRAPHICS
Use the table below to answer the next question.
Force
Acceleration
35 N
5 m/s2
70 N
10 m/s2
105 N
15 m/s2
15. Evaluating The table shows the acceleration produced by applying
different forces on a 7 kg mass. Assuming that the pattern continues, predict
what force would be needed to produce an acceleration of 25 m/s2 .
WRITING SKILLS
16. Writing a Biography Describe the significance of Newton’s Principia books.
Describe what information was presented in Principia and why this
information was important to scientists everywhere.
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Holt California Physical Science
45
Forces and Motion
Name
Class
Date
Chapter Review continued
CRITICAL THINKING
17. Concept Mapping Use the following terms to create a concept map: gravity,
free fall, terminal velocity, projectile motion, and air resistance.
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Holt California Physical Science
46
Forces and Motion
Name
Class
Date
Chapter Review continued
18. Identifying Relationships During a space-shuttle launch, about 830,000 kg of
fuel are burned in 8 min. The fuel provides the shuttle with a constant thrust,
or forward force. How does Newton’s second law of motion explain why the
shuttle’s acceleration increases as the fuel is burned?
19. Applying Concepts Suppose that you are standing on a skateboard and you
toss a backpack full of books toward your friend. What do you think will happen to you? Explain your answer in terms of Newton’s third law of motion.
INTERPRETING GRAPHICS
Use the image below to answer the next two questions.
Earth
Moon
Sun
20. Applying Concepts The image shows the paths of Earth and the moon.
Explain how you can use the image to prove that Earth and the moon are
accelerating.
21. Identifying Relationships Identify the forces responsible for maintaining the
relative positions of these bodies in the solar system.
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Holt California Physical Science
47
Forces and Motion
Name
Class
Date
Chapter Review continued
INTERPRETING GRAPHICS
Use the image below to answer the next two questions.
22. Applying Concepts The arrows in the image show the force of gravity and the
force of air resistance on an acorn. Is the acorn accelerating? Explain your
answer.
23. Making Inferences Under what conditions would the acorn stop accelerating
yet still continue to fall?
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Holt California Physical Science
48
Forces and Motion
Name
Class
Date
Chapter Review continued
MATH SKILLS
24. Using Equations A rock falls from rest off a cliff and hits the ground in 1.5 s.
Without considering air resistance, determine the rock’s velocity as the rock
hits the ground. Show your work below.
CHALLENGE
25. Forming Hypotheses Suppose that you are looking at an orange tree. Several
oranges are hanging from the tree. Suddenly, an orange falls to the ground.
Form a hypothesis that explains why the orange fell. Use Newton’s first law of
motion in your hypothesis.
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Holt California Physical Science
49
Forces and Motion
TEACHER RESOURCES
11. The feather and the hammer would hit
7. Sample answer: During a head-on
the moon’s surface at the same time
because there is no air resistance.
12. A parachute reduces the acceleration of a skydiver by increasing air
resistance, which allows a skydiver to
descend with less velocity. Without the
parachute, acceleration due to gravity
would cause the skydiver’s velocity to
increase as he or she approaches the
ground. If a skydiver opens the parachute too close to the ground, he or
she may have already reached such a
high velocity that there is not enough
time for the parachute to reduce the
velocity before landing. In that case,
it is too late for the parachute to be
effective.
collision, an unbalanced force stops
the motion of the car. But because no
unbalanced force immediately acts
on the people inside the car, they
continue to move forward. Air bags
are important because they provide
unbalanced forces to stop the motion
of the people in the car. The air bags
prevent the people from hitting the
dashboard or windshield of the car.
8. The black arrow represents the force
that the hand exerts on the table. The
white arrow represents the equal and
opposite force that the table exerts on
the hand.
9. The acceleration of the wagon will be
less with my friend’s brother in the
wagon than it was before he climbed
in because he added more mass to the
wagon. Because the wagon containing
both people has a greater mass than
the wagon containing only my friend, I
must apply more force to achieve the
same rate of change in motion.
SECTION: NEWTON’S LAWS OF
MOTION
1. Sample answer: Inertia is the
2.
3.
4.
5.
6.
tendency of an object to resist changes
in motion.
When the forces on an object are
unbalanced, the velocity of the object
could increase, the velocity could
decrease, or the object’s direction of
motion could change.
When the forces on an object are balanced, the motion of the object will
not change. Objects that are at rest
will stay at rest and objects that are in
motion will stay in motion.
Newton’s second law states that the
acceleration of an object increases
as the force acting on the object
increases, but the acceleration
decreases as the mass of the object
increases.
If there were no friction between a
rolling ball and the ground, the ball
would not stop rolling. Friction is the
unbalanced force acting on the ball to
change its motion.
The action and reaction forces do not
balance each other because the forces
are acting on two different objects.
Because they act on two different
objects, you cannot combine them to
determine the net force.
Chapter Review
1.
2.
3.
4.
5.
6.
7.
8.
B
inertia
terminal velocity
weight
C
D
B
Sample answer: A feather falling inside
a vacuum is in free fall. An object
dropped on the moon is in free fall.
9. Gravity and air resistance combine to
give a net force on the falling object.
When gravity and air resistance are the
same size but in opposite directions,
the object stops accelerating downward and reaches its terminal velocity.
10. Friction is a force that opposes the
motion of objects. Friction slows the
motion of objects so you don’t see
objects moving forever in a straight
line.
11. The magnitude of the gravitational
force would decrease because the
distance between the sun and Earth
would be greater than the current
distance between the sun and Earth.
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Holt California Physical Science
135
Forces and Motion
TEACHER RESOURCES
12. Action and reaction forces do not can-
23. The acorn will stop accelerating when
cel out because these forces do not act
on the same object.
The down arrow indicates the force
of gravity; the up arrow indicates the
elastic forces due to tension in the
electric cord.
Because the motion of the light bulb is
not changing, we know that the forces
are balanced.
175 N; For every 35 N of force that is
applied, the acceleration increases by
5 m/s2 .
(25 m/s2 )/(5 m/s2 ) 5
and 5 35 N 175 N
or (25 m/s2 15 m/s2 ) 10 m/s2
105 N 70 N 175 N
Students’ biographies should state
that the Principia books included
Newton’s laws of motion and the
universal law of gravitation. Answers
should also indicate that scientists still
use the ideas presented in Principia
to do research and solve problems.
An answer to this exercise can be
found at the end of the Teacher
Edition.
During takeoff, the shuttle burns fuel
and therefore loses mass. However, the
forward force on the shuttle remains
the same. So, the shuttle’s acceleration
increases because its mass constantly
decreases during takeoff.
I will move away from my friend (in
the opposite direction of the backpack). The action force is my pushing
the backpack toward my friend. The
reaction force is the backpack pushing
me away from my friend.
Neither Earth nor the moon is traveling in a straight path, so an unbalanced force must be acting on each.
Therefore, each must be accelerating.
Gravity provides the centripetal force
that keeps the moon in orbit around
Earth, and Earth in orbit around the
sun.
Yes, it is accelerating. The downward
force of gravity indicated by the down
arrow is greater than the upward force
of air resistance indicated by the up
arrow. So, the acorn is accelerating
downward.
it reaches its terminal velocity. This
would occur if the upward force of air
resistance becomes equal to the
downward force of gravity. Then, the
acorn would stop accelerating and
continue to fall at a constant velocity.
24. v g t 9.8 m/s2 1.5 s 14.7 m/s
25. Sample answer: If the forces on the
orange were unbalanced, the orange
would fall from the tree. While the
orange is static, the upward force of
the tree on the orange balances the
force of gravity. When the orange
breaks away from the tree, the force
of gravity is an unbalanced force that
acts on the orange and causes the
motion of the orange to change.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
Section Quizzes
SECTION: GRAVITY: A FORCE OF
ATTRACTION
1.
2.
3.
4.
5.
6.
7.
8.
9.
B
C
A
B
D
C
A
C
B
SECTION: GRAVITY AND MOTION
1.
2.
3.
4.
5.
6.
7.
8.
9.
C
B
A
B
A
C
C
B
B
SECTION: NEWTON’S LAWS OF
MOTION
1.
2.
3.
4.
5.
6.
D
A
C
B
B
C
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Holt California Physical Science
136
Forces and Motion