Table of Contents
Introduction to MSA Finish Line Science 5 . . . . . . . . . . . . . . . . . . . . . . . . 5
UNIT 1 The Practice of Science. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Lesson 1 Scientific Investigations [1.A.1.c, f; 1.C.1.d] . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Lesson 2 Gathering Data [1.A.1.a, b, g] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Lesson 3 Presenting Data [1.C.1.a] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Lesson 4 Drawing Conclusions [1.A.1.a; 1.B.1.a, b, c; 1.C.1.d] . . . . . . . . . . . . . . . . . . . . . 27
The Practice of Science Review . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
UNIT 2 The Science of Earth and Space . . . . . . . . . . . . . . . . . . . . . . . . . 39
Lesson 1 Weathering, Erosion, and Deposition [(4)2.A.2.a, b; (5)2.A.2.c; (5)2.A.3.c] . . . . 40
Lesson 2 Rapid Changes on Earth’s Surface [(5)2.A.2.a] . . . . . . . . . . . . . . . . . . . . . . . 47
Lesson 3 Rocks, Minerals, and Soils [(5)2.A.3.b] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
Lesson 4 Fossils [(4)2.B.2.a, c] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
Lesson 5 The Water Cycle [(5)2.E.1.a, b] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
Lesson 6 The Sun and Other Stars [(4)2.D.1.b, e] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
Lesson 7 Planet Earth [(5)2.D.1.b; (5)2.D.2.b, d] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
The Science of Earth and Space Review . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
UNIT 3 The Science of Life, Part 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
Lesson 1 Classification of Life [(4)3.A.1.b, c, d] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
Lesson 2 Cells [(5)3.B.2.b, c] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
Lesson 3 Getting Energy [(4)3.E.1.b] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
Lesson 4 Inherited and Acquired Traits [(4)3.C.1.b] . . . . . . . . . . . . . . . . . . . . . . . . . 105
Lesson 5 Change Over Time [(4)3.D.1.a, b] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
The Science of Life, Part 1 Review . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116
UNIT 4 The Science of Life, Part 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
Lesson 1 Organisms and Their Environments [(5)3.A.1.a, b] . . . . . . . . . . . . . . . . . . 122
Lesson 2 Food Chains and Food Webs [(5)E.1.a, b; (4)3.F.1.a] . . . . . . . . . . . . . . . . . . . 129
Lesson 3 Ecology [(4)3.F.1.a] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134
Lesson 4 Changing Habitats [(4)3.F.1.b] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140
The Science of Life, Part 2 Review . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145
UNIT 5 The Science of Chemistry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149
Lesson 1 Matter [(4)4.A.1.b, d] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150
Lesson 2 Conservation of Mass [(5)4.B.1.b, c] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156
Lesson 3 States of Matter [(5)4.C.1.a, b] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161
Lesson 4 Mixtures and Compounds [(5)4.D.1.a, b] . . . . . . . . . . . . . . . . . . . . . . . . . . 167
The Science of Chemistry Review . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173
UNIT 6 The Science of Physics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177
Lesson 1 Motion [(5)5.A.1.a, b] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178
Lesson 2 Force and Motion [(5)5.A.2.a, b] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185
Lesson 3 Heat [(4)5.B.1.a, b] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191
Lesson 4 Electricity [(4)5.C.2.b, c, d] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 196
Lesson 5 Magnetism [(4)5.C.3.a, b] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201
Lesson 6 Light and Mirrors [(5)5.D.3.a, b] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205
The Science of Physics Review. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 210
UNIT 7 The Science of the Environment . . . . . . . . . . . . . . . . . . . . . . . . 215
Lesson 1 Natural Resources [(5)6.A.1.a, b, c; (4)6.B.1.a]. . . . . . . . . . . . . . . . . . . . . . . . . 216
Lesson 2 How Humans Affect the Environment [(5)6.B.2.a, b, c] . . . . . . . . . . . . . . . 223
The Science of the Environment Review. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229
LESSON
LESSON
2
2
Force and Motion
Objectives (5)5.A.2.a, b
Remember that motion is change in position over time, and
that there are different kinds of motion. Two kinds of motion are
uniform motion and variable motion. When something moves with
uniform motion, its speed and direction do not change. When
something moves with variable motion, its speed, its direction, or
both are changing.
There is an important difference between these two kinds of
motion. For an object to move with variable motion, a force must
act on it. If an object is moving with uniform motion, no force is
acting on it. When two or more forces exactly cancel each other,
the effect is the same as no force. So, when all the forces on an
object cancel, the object will either not move or will move with
uniform motion.
A force is a push or a
pull.
What Is a Force?
A force is a push or a pull. You know what it feels like to pull a
door open or push a door shut. When you open or close a door,
you are exerting, or applying, a force.
Forces can change the motion of an object in three basic ways:
• It can make the object move more quickly.
• It can make the object move more slowly.
• It can make the object move in a different direction.
It is important to understand that none of these changes in
motion can happen without a force. The soccer player below is
about to make the ball move by applying a force to it by kicking it.
The ball will move faster
and faster as long as the player’s
foot is in contact with the ball.
During that short time, the
player’s foot applies a pushing
force. After the ball is moving,
another player could slow the
ball down and stop it by
applying another force. A player
could also use the force of a
kick to change the direction of
the ball’s motion without
changing its speed.
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The same force will not change the motion of every object by
the same amount. For example, if the player kicked a watermelon,
it would not speed up very much compared with the soccer ball. If
the player kicked a tennis ball, it would speed up more than the
soccer ball. The reason for the difference is that a watermelon has
more mass than a soccer ball or a tennis ball. The watermelon’s
greater mass means that the same kick will cause less of a change
to its motion. This example shows an important rule of physics: The
greater the mass of an object, the less a given force will change the
object’s motion.
There are two main ways to think about this rule. The first way
is to remember that the greater the mass of an object, the more
force is needed to get the same change in motion. The soccer
player would have to kick a watermelon with a lot more force to
make it move as fast as the soccer ball.
The tennis ball has the least mass, and the
watermelon has the most mass.
The second way to think about this rule is to remember that the
greater the force applied to a given object, the more its motion will
change. The harder the soccer player kicks the ball, the more the it
will speed up. The harder you pull on a door, the faster it will open.
Which of these objects would you have to push on with the
most force to make it begin to move across a wooden floor?
A a pillow
C a loaf of bread
B a book
D a concrete block
Remember, the greater the mass, the more force is needed to get
the same change in motion. A concrete block has more mass
than any of the other objects, so the correct choice is D.
Gravity
All objects with mass attract, or pull on, each other with a force
called gravity. The strength of gravity between two objects
depends on the masses of the objects and the distance between
them. As the masses of the objects increase, the force of gravity
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Gravity is the force of
attraction between two
objects. Gravity is always
a pull, never a push. The
force of gravity is also
sometimes called
gravitational force.
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between them increases. As the distance between the objects
increases, the force of gravity between them decreases. The change
in the force of gravity as objects near Earth’s surface rise and fall is
extremely tiny. So, scientists generally say that the force of gravity is
a constant near Earth’s surface.
Compared with other forces around us, gravity is a very weak
force. That is why you don’t feel yourself being pulled toward the
person sitting next to you. You are close together, but your masses
are small. However, Earth has a large mass, and we are close to it,
so we can feel the pull between Earth and ourselves. No matter
how high you jump, the force of gravity will always pull you back to
Earth.
The sun has much more mass than Earth does, but it is very far
away. The moon is much closer than the sun, but its mass is less
than that of Earth. So, the gravity between Earth and us is much
greater than the gravity between us and the moon and us and the
sun. That’s why we do not fly off Earth toward the sun or moon.
However, the sun and moon do pull on everything on Earth. For
example, the sun’s gravity and moon’s gravity cause tides.
The moon travels in a
circle around Earth.
Because the moon moves
along a circular path, it
is always changing
direction. If the moon is
changing direction, a
force must be acting on
it. This force is gravity.
Remember that a force can cause an object to speed up, slow
down, or change direction. When you throw a ball into the air, the
force of gravity causes all three of these changes. As the ball goes
up, gravity slows it down more and more until it stops. Then, it
changes direction and begins to fall toward the ground. On the
way down, the force of gravity makes the ball move faster and
faster as it falls back to the ground.
Path of ball
Force of gravity
Where could you jump higher: on Earth or on the moon?
Explain your answer.
Remember that the moon has much less mass than Earth does.
So, the force of gravity between you and the moon would be less
than the force of gravity between you and Earth. Because the
force of gravity on you would be less on the moon, you could
jump higher on the moon than you are able to do on Earth.
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Friction
Friction is another force that affects us every day. Friction is the
force between things that are touching one another. Friction acts
against motion; that is, friction can make moving things slow down.
It can also prevent nonmoving things from moving. When one
surface moves past another, friction acts to slow down the
movement. Friction is also the force that holds things on slopes.
Cars parked on steep streets do not slide to the bottom because the
force of friction between the tires and the pavement is greater than
the force of gravity pulling the car toward the bottom of the hill.
Friction is a force that
acts between two
objects that are touching
each other. Friction acts
against motion.
The force of friction is greater for rough surfaces than for
smooth surfaces. The force of friction is also greater for sliding
objects than for rolling objects. The force of friction between a
brick and a carpet is much greater than the force between a
marble and a hardwood floor. However, no matter how smooth the
surface is, there is always some friction. Eventually, friction will
cause any object on Earth to stop moving.
Maxine places several objects on a board. She lifts one end
of the board slowly, making the slope steeper and steeper.
Which of these objects would probably be the first to slide
down the board?
A a brick
C a concrete block
B a book
D a piece of cake
Friction between each object and the board keeps the object
from sliding down the board. So, the object that will slide down
the board first will be the one that produces the least friction
with the board. Remember that the force of friction is less for
smoother things. Of the four objects, a book is the smoothest. The
correct choice is B.
Friction does not occur only between solids. Liquids and gases
can produce friction, too. For example, when an object moves
through air, there is friction between the object and the air. This
friction slows the object down.
Imagine a skydiver falling through the air with a parachute on.
The force of gravity pulls the skydiver downward. At the same time,
the force of friction between the parachute and the air pushes the
skydiver upward. When these two forces are equal, the skydiver
falls with uniform motion. She does not speed up or slow down.
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It’s Your Turn
Please read each question carefully. To answer multiple-choice questions, circle the correct
response. To answer constructed response questions, write your answer in the space provided.
Use the picture below to answer question 1.
1 Tanya kicks a soccer ball. It flies into the air and then comes
back to the ground. The picture shows the path of the soccer
ball. Which of these best describes the force of gravity while
the ball is in the air?
A
It reverses when the ball starts to fall.
B
It increases as the ball moves upward.
C
It decreases as the ball starts to come down.
D
It is the same the whole time the ball is moving.
2 Each of the following vehicles speeds up by the same amount.
Which required the most force to speed up?
A
a bicycle
C
a medium-sized van
B
a pickup truck
D
a tractor-trailer truck
3 Kyle rolled a ball along the floor. After a while, the ball slowed
down and stopped. Which of these best explains why the ball
did not keep rolling?
A
All the forces on the ball were equal.
B
The force of friction acts against the ball’s motion.
C
There were no forces acting on the ball as it rolled.
D
The force of gravity pushes the ball away from the floor.
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Use the picture below to answer question 4.
4 Carrie and Dev are trying to move this bookshelf. They push
against one side of the bookshelf, but it does not move. How
could Carrie and Dev move the bookshelf more easily? In your
answer, be sure to
• identify the force that is preventing the bookshelf from
moving
• describe some ways they could make the bookshelf
move
• explain how each of these ways would make the
bookshelf easier to move
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