Review and Assessment
PHSchool.com
For: Self-Assessment
Visit: PHSchool.com
Web Code: cxa-3100
Review and Assessment
Target Reading Skill
Target Reading Skill
Take Notes In your notebook, create a
two-column note-taking organizer for
Section 4. Include summary statements.
Check students’ notes for accuracy.
Recall Clues
& Questions
Notes
What is
friction?
Friction—a force that two surfaces
exert on each other
Reviewing Key Terms
1. a 2. c
3. c 4. a 5. a
6. equal forces acting on an object in
opposite directions
7. the types of surfaces involved
8. the objects’ masses and distances
9. the leaf has a greater surface area
10. its mass and velocity
Strength depends on
• types of surfaces
• how hard they are
pushed together
Choose the letter of the best answer.
1. When an unbalanced force acts on an object,
the force
Complete the following sentences so that
your answers clearly explain the key terms.
6. When two people push on a box and the box
a. changes the motion of the object.
b. is canceled by another force.
c. does not change the motion of the object.
d. is equal to the weight of the object.
2. Which of the following is an elastic force?
a. friction
b. gravity
c. tension
d. air resistance
3. Which of the following is not a projectile?
a. a satellite
b. a thrown ball
c. a ball on the ground
d. a soaring arrow
4. The resistance of an object to any change in its
motion is called
a. inertia.
b. friction.
c. gravity.
d. weight.
5. The product of an object’s mass and its
acceleration is called the
a. net force.
b. weight.
c. momentum.
d. gravitation.
does not move, this is an example of balanced
forces, which are
.
7. Friction depends upon how hard the surfaces
are pushed together and
.
8. A force that pulls objects toward each other
is called gravity, which depends upon
.
9. The force of air resistance is greater on a leaf
than an acorn because
.
10. The momentum of an object depends on
.
Checking Concepts
Descriptive Paragraph Suppose you have
been asked to design a new amusement park
ride. Write a description of how you will
design it. Explain the role that friction and
gravity will play in the ride’s design.
Forces
Chapter 10 ◆ 407
E-LA: Writing 8.2.0
Writing Mode Descriptive
Scoring Rubric
4 Exceeds criteria; includes a detailed
description of an amusement park ride with
a thorough and correct explanation of the
role of gravity and friction
3 Meets criteria
2 The paragraph lacks detail and/or
includes information about only gravity or
only friction
1 The paragraph does not relate gravity and
friction to the amusement park ride and/or
contains numerous errors
Video Assessment
L2
Forces
Show the Video Assessment to review
chapter content and as a prompt for the
writing assignment. Discussion questions:
What force accelerates a roller coaster train
that is going downhill? (Gravity) What
force helps a roller coaster to stop?
(Friction)
Diagnose and Remediate
Standard
Review and
Assessment Items
Standards-Targeted Resources
Additional Resources
S 8.2.d
2, 7, 8, 9, 12, 13, 16, 17,
18, 19, 20, 25
RNG-A 174–178, 187; RNG-B 153–156, 166;
Video Field Trip
TR: Vocabulary Skill
S 8.2.e
1, 3, 5, 10, 14, 15, 16, 18,
19, 23, 24, 25
AA cgp-3024; RNG-A 171–173, 179–181, 182–184,
185–187; RNG-B 150–152, 157–159, 160–163,
164–166; Video Field Trip
Student Edition in MP3
(English/Spanish)
S 8.2.f
4, 5, 7, 9, 10, 14, 18, 19,
20, 21, 22
RNG-A 179–181; RNG-B 157–159, 160–163
Student Express with Interactive
Textbook CD-ROM
TR: Key Terms
407
Checking Concepts
Review and Assessment
11. The forces the four children are exerting
on the object balanced one another.
12. Fluid friction is usually less than sliding
friction. By bathing the parts of the machine
in oil, friction is reduced.
13. The yo-yo exerts a downward force on
the string. Whatever or whomever is holding
the string exerts an equal upward force.
14. Newton’s second law states that force is
equal to mass multiplied by acceleration.
15. You can throw your empty jet pack away
from the space station. As a result, the
reaction force exerted on you by the jet pack
will accelerate you toward the space station.
16. Students’ drawings should resemble the
art in Figure 21, with Earth’s gravitational
force directed toward the center of Earth and
perpendicular to the satellite’s motion. Yes,
the satellite is accelerating because it is
changing direction.
Thinking Critically
17. When you squeeze a sponge you use
compression.
18. The skateboard stops, but your inertia
causes you to keep moving forward.
19. The net force is 90 N to the right. The
acceleration is 9 m/s2.
20. The friction force is equal to the pushing
force because the book moves at a constant
velocity.
Checking Concepts
Math Practice
11. Four children pull on the same toy at the same
21. Calculating Force A 7.3-kg bowling ball
time, yet there is no net force on the toy. How
is that possible?
12. Why are parts of machines that slide over each
other often bathed in oil?
13. A yo-yo is hanging motionless from a string.
Identify and describe the forces exerted on the
string.
related by Newton’s second law of motion.
15. Suppose you are an astronaut making a space
walk outside your space station when your jet
pack runs out of fuel. How can you use your
empty jet pack to get you back to the station?
satellite around Earth. Draw the force vectors
acting on the satellite. Is the satellite
accelerating?
Thinking Critically
17. Classifying What is the name of the force you
exert on a sponge when you squeeze it?
18. Applying Concepts You are moving fast on a
skateboard when your wheel gets stuck in a
crack on the sidewalk. Using the term inertia,
explain what happens.
19. Problem Solving Look at the diagram below
of two students pulling a bag of volleyball
equipment. The friction force between the
bag and the floor is 15 N. What is the net force
acting on the bag? What is the acceleration of
the bag?
45 N
60 N
momentum
22. (240 + 75) kg 16 m/s = 5,040 kg•m/s
0 m/s = 0 kg·m/s; left ball after: 0.4 kg 0.5 m/s = 0.2 kg·m/s; right ball after:
0.4 kg 1.5 m/s = 0.6 kg·m/s
24. Total momentum before: 0.8 kg·m/s +
0 kg·m/s = 0.8 kg·m/s; total momentum
after: 0.2 kg·m/s + 0.6 kg·m/s = 0.8 kg·m/s;
Yes, the law of conservation is satisfied. The
total momentum before the collision is equal
to the total momentum after the collision.
25. Students’ designs will vary, but should
include a high-friction surface to
demonstrate how friction will decrease
momentum.
408
mobile travels at 16 m/s. The mass of the
driver is 75 kg. What is the momentum of the
snowmobile and driver?
Applying Skills
Use the illustration showing a collision
between two balls to answer Questions 23–25.
Before
2 m/s
0 m/s
After
0.5 m/s
1.5 m/s
16. Draw a diagram showing the motion of a
21. 7.3 kg 3.7 m/s2 = 27.01 N;
Applying Skills
22. Calculating Momentum A 240-kg snow-
14. Explain how force, mass, and acceleration are
Math Practice
23. Left ball before: 0.4 kg 2 m/s =
0.8 kg·m/s; right ball before: 0.4 kg accelerates at a rate of 3.7 m/s2. What force acts
on the bowling ball?
10 kg
15 N
20. Relating Cause and Effect If you push a book
across a table at a constant velocity, is the
friction force less than, equal to, or more than
your pushing force? How do you know?
408 ◆
23. Calculating Use the formula for momentum
to find the momentum of each ball before and
after the collision. Assume the mass of each
ball is 0.4 kg.
24. Inferring Find the total momentum before
and after collision. Is the law of conservation
of momentum satisfied in this collision?
Explain.
25. Designing Experiments Design an
experiment in which you could show that
momentum is not conserved between the
balls when friction is strong.
Performance Assessment Test your vehicle to
make sure it will work on the type of floor in your
classroom. Will the vehicle stay within the bounds
set by your teacher? Identify all the forces acting
on the vehicle. What was the most significant
source of friction for your vehicle? List at least
three features you included in the design of the
vehicle that led to an improvement in its
performance. For example, did you give it a
smooth shape for low air resistance?
Choose the letter of the best answer.
6. The table below shows the mass of and net
1. Which of the following is determined by the
force of gravity?
A weight
B momentum
C mass
D distance
Teachers can monitor student progress and
supply remediation when necessary.
Calculating Acceleration
Object
Net Force (N)
Mass (kg)
S 8.2.d
2. When an object is pulled across a level surface
at a constant velocity, what force is the pulling
force equal to?
A gravity
B friction
C inertia
D an unbalanced force
S 8.2.e
3. What force makes it less likely for a person to
slip on a dry sidewalk as opposed to an icy
sidewalk?
A air resistance
B friction
C inertia
D momentum
S 8.2.e
Use the diagram below to answer questions
4 and 5.
Force Force
force on four objects. Which object has the
greatest acceleration?
Boulder
1,000
100
Suitcase
20
20
Shopping cart
25
50
2
1
Book
A
B
C
D
boulder
suitcase
shopping cart
book
Standards Practice
1. A; S 8.2.d
2. B; S 8.2.e
3. B; S 8.2.e
4. C; S 8.2.a
5. D; S 8.2.e
6. A; S 8.2.f
7. C; S 8.2.c
S 8.2.f
7. In a game of tug-of-war, you pull on the rope
with a force of 100 N to the right and your
friend pulls on the rope with a force of 100 N
to the left. What is the net force on the rope?
A 200 N to the right
B 200 N to the left
C 0N
D 100 N to the right
S 8.2.c
Motion
8. The forces are unbalanced because one is
greater than the other. The net force is
10N to the right. The velocity would
change because an unbalanced force on an
object affects the object’s velocity. The
bone would move to the right.
S 8.2.b, 8.2.f
4. What conclusion can you draw by looking at
the diagram?
A Air resistance in front of the balloon pushes
it backward.
B Gravity forces air out of the balloon’s
open end.
C The force of the air leaving the balloon
causes it to accelerate forward.
D Friction causes the balloon’s acceleration to
decrease.
S 8.2.a
8. Two dogs are pulling on opposite ends of a
bone. One dog pulls to the right with a force of
50 N while the other pulls to the left with a
force of 40 N. Are the forces on the bone
balanced or unbalanced? How do you know?
What is the net force on the bone? Would the
bone’s velocity change? Why?
S 8.2.b, S 8.2.f
5. In the diagram above, why don’t the two forces
cancel each other out?
A They are not equal.
B They both act on the air.
C They both act on the balloon.
D They act on different objects.
S 8.2.e
Chapter 10
◆ 409
S 8.2.a, 8.2.e
Performance Assessment Provide
time for students to test their vehicles.
Remind students to include diagrams
identifying forces on the vehicles. After all of
the presentations are complete, have
students discuss the source of friction for the
different vehicles. Encourage students to
incorporate Newton’s laws of motion when
they explain the features of their designs that
improved performance. Also, encourage
them to compare design features with their
classmate’s vehicles as they evaluate their
own vehicles.
Teaching Resources
Laboratory Manual TE
• Standards Investigation Scoring Rubric
The Standards Investigation Scoring Rubric
will help you evaluate students’ work. If you
share the rubric in advance, students will
know what is expected of them.
409