Lesson 1 | Gravity and Friction
Student Labs and Activities / Page / Appropriate For:Launch Lab / 8 / all students
Content Vocabulary / 9 / all students
Lesson Outline / 10 / all students
MiniLab / 12 / all students
Content Practice A / 13 /
Content Practice B / 14 /
School to Home / 15 / all students
Key Concept Builders / 16 /
Enrichment / 20 / all students
Challenge / 21 /
Assessment
Lesson Quiz A / 22 /
Lesson Quiz B / 23 /
/ Approaching Level / / On Level / / Beyond Level / / English-Language Learner
Teacher evaluation will determine which activities to use or modify to meet anystudent’s proficiency level.
The Laws of Motion7
Name Date Class
LESSON 1: 5 minutes
Can you make a ball move without touching it?
You can make a ball move by kicking it or throwing it. Is it possible to make the ball move
even when nothing is touching the ball?
Procedure
1.Read and complete a lab safety form.
2.Roll a tennis ball across the floor.
Think about what makes the ball move.
3.Toss the ball into the air. Watch as it
moves up and then falls back to your
hand.
4.Drop the ball onto the floor. Let it
bounce once, and then catch it.
Think About This
1.What made the ball move when you rolled, tossed, and dropped it? What made it stop?
2.Key Concept Did something that was touching the ball or not touching the ball
cause it to move in each case?
8The Laws of Motion
Name Date Class
LESSON 1
Gravity and Friction
Directions: Use the clues and the terms listed below to complete the puzzle. NOTE: There is no empty square in
the puzzle between the words of two-word terms.
noncontact force / significant / static / weight
Clues
Across
6.the amount of matter in an object
9.Gravity is an example of this kind
of force.
Down
1.a force that resists the motion of two
surfaces that are touching
2.the gravitational force exerted on an
object
3.an attractive force that exists between
all objects that have mass
4.at rest
5.important
7.a push or pull on an object by another
object that is touching it
8.a push or a pull
The Laws of Motion 9
Name Date Class
LESSON 1
Gravity and Friction
A.Types of Forces
1.A push or a pull is called a(n) .
2.A(n) is a push or a pull on an object by another object
that is touching it.
3.A force that one object can apply to another object without touching it is
a(n) .
4.Gravity, , and electric forces are examples of
noncontact forces.
5.Forces have and
6.An arrow can be used to show a force; the shows the
strength of the force, and the direction of the arrow shows the
of the force.
7.Forces are measured in units called .
B.What is gravity?
1.is the amount of matter in an object.
2.is an attractive force that exists between all objects that
have mass.
3.Mass is often measured in .
4.According to the law of , all objects are attracted to one
another with a gravitational force that is proportional to the mass of the objects
and the distance between them.
a.When the mass of one or both objects increases, the gravitational force between
the objects .
b.When the distance between two objects increases, the attraction between the
objects .
5.is the gravitational force exerted on an object.
a.Near Earth’s surface, an object’s weight is the gravitational force exerted on the
object by .
b.The of an object on Earth decreases significantly only
when the object moves a great distance away from Earth.
10The Laws of Motion
Name Date Class
Lesson Outline continued
C.Friction
1.is a force that resists the motion of two surfaces that are
touching.
2.friction prevents surfaces from sliding past each other.
3.Up to a limit, the of static friction changes to match
the applied force.
4.friction opposes the motion of surfaces sliding past
each other.
a.When an object is sliding, the force of sliding friction does not
; for this reason, increasing the applied force makes
a sliding object move .
b.If you stop pushing a sliding object, the object will eventually
due to sliding friction.
5.is friction between a surface and a fluid, such as air
or water.
a.Fluid friction between an object and air is called .
b.Decreasing an object’s surface area by changing its shape
the object’s air resistance.
6.One reason for friction between surfaces is the , or the
dips and bumps on one surface that catch on those of the other surface.
7.One reason for friction between surfaces is that atoms and molecules with
charges attract each other.
8.decrease friction by causing a slight separation between
solid surfaces, so they don’t contact each other.
The Laws of Motion11
Name Date Class
LESSON 1: 10 minutes
How does friction affect motion?
Friction affects the motion of an object sliding across a surface.
Procedure
1.Read and complete a lab safety form.
2.Use tape to fasten sandpaper to a
table. Attach a spring scale to a
wooden block with an eyehook in it.
3.In the Data and Observations below,
record the force required to gently pull
the block at a constant speed on the
sandpaper and then on the table.
Data and Observations
Analyze and Conclude
1.Compare the forces required to pull the block across the two surfaces.
2.Key Concept How did reducing friction affect the motion of the block?
12The Laws of Motion
Name Date Class
LESSON 1
Gravity and Friction
Directions: On the line before each definition, write the letter of the term that matches it correctly. Each term is
used only once.
1.a push or a pull on an object
2.push or pull on one object by another object
3.applied without touching
4.makes hair stand on end
5.keeps you from floating away
6.makes a compass needle point north
7.unit of mass
8.unit of force or weight
9.resists the motion of two surfaces that are
touching
10.reduces friction
A.noncontact force
B.friction
C.electric force
D.gravity
E.lubricant
F.force
G.newton
H.contact force
I.magnetic force
J.kilogram
The Laws of Motion13
Name Date Class
LESSON 1
Gravity and Friction
Directions: Answer each question or respond to each statement on the lines provided.
1.Define the terms below.
a.force
b.contact force
c.noncontact force
2.What are three noncontact forces?
3.What are the units for mass and weight?
4.What is the difference between mass and weight?
5.Explain how the gravitational force between two objects is affected by their mass and
the distance between them.
6.What is friction?
7.What are the three kinds of friction discussed in the lesson?
14The Laws of Motion
Name Date Class
LESSON 1
Gravity and Friction
For this activity, you will need a small object that you can slide across a surface, such as a
bottle cap or a coin. You will also need a ruler or a measuring tape and a pencil.
Prediction / Trial 1 / Trial 2 / Trial 3
1.Locate four flat surfaces in or around your home that would exert different amounts
of friction on a sliding object. Record the surfaces in the Surface column. Examples of
surfaces include a carpeted floor, a tile floor, and a glass tabletop.
2.Predict how much friction each surface will exert on an object sliding across it. In the
Prediction column, rank the surfaces from 1 to 4. Write 1 for the surface you expect to
exert the most friction and 4 for the surface you expect to exert the least.
3.Push the object across the first surface three different times. Use the ruler to measure
the distance it slides during each trial and record each distance in the table. Try to
apply the same amount of force each time. Repeat this step for each surface.
4.Which surface exerted the most friction on the object? How do you know?
5.Did you correctly predict which surface would exert the most and least friction on the
object? Explain.
The Laws of Motion15
Name Date Class
LESSON 1
Gravity and Friction
Key Concept What are some contact forces and some noncontact forces?
Directions: On the line before each motion, write C if it is caused by a contact force or N if it is caused by
a noncontact force.
1.rain falling
2.papers scattered by wind
3.a baseball sailing into the outfield
4.a magnet attracting a nail
5.rocks tumbling down a mountain
6.an elevator ascending
7.an arrow flying toward a target
8.lightning striking a building
9.a brick wall collapsing
10.a meteorite hitting Earth
Directions: Answer each question on the lines provided.
11.What is a force?
12.What is a contact force?
13.What is a noncontact force?
14.What is the unit of force?
16The Laws of Motion
Name Date Class
LESSON 1
Gravity and Friction
Key Concept What is the law of universal gravitation?
This diagram represents a star orbited by two planets—planet A and planet B. The star is
also orbited by a mysterious object, object X, that entered into the star’s gravitational field.
Directions: Use the diagram to answer each question or respond to each statement.
1.The gravitational force between the star and planet A is the same as the gravitational
force between the star and planet B. Explain why this is true.
2.The gravitational force between the star and object X is equal to the forces between the
star and the two planets. From that information, what can you conclude about object X?
Directions: Answer each question on the lines provided.
3.What is gravity?
4.What happens to the gravitational attraction between two objects as the distance
between them increases?
The Laws of Motion17
Name Date Class
LESSON 1
Gravity and Friction
Key Concept What is the law of universal gravitation?
Directions: Complete this concept map by choosing terms from the word bank and writing them in the correct spaces.
effectforcegravitymassnewtonobjectunit
Directions: On the line before each statement, write T if the statement is true or F if the statement is false.
8.An object that has twice as much mass as another weighs four times as much.
9.Near Earth’s surface, the weight of an object in newtons is about 10 times its
mass in kilograms.
10.The weight of an astronaut in orbit is about 90 percent of the astronaut’s
weight on Earth.
18The Laws of Motion
Name Date Class
LESSON 1
Gravity and Friction
Key Concept How does friction affect the motion of two objects sliding past each other?
Directions: On each line, write the term from the word bank that correctly completes each sentence. Each term is
used only once.
electricalfluidlubricantsmicroscopic
movementresistanceslidingstatic
1.Friction is a force that opposes .
2.To push a heavy crate across a floor, you must first overcome
friction, which tends to hold it in place.
3.After overcoming that form of friction, you must push against
friction.
4.Friction between a surface and air or a liquid is called
friction.
5.Air friction on a car or airplane is also called air .
6.Friction between solid surfaces is caused mostly by roughness on a(n)
scale.
7.Friction can also be caused by attraction between particles.
8.Friction between solid surfaces can be reduced with
The Laws of Motion19
Name Date Class
LESSON 1
Force at a Distance
Lobsters know their way home, and
researchers who studied lobster behavior
believe it is due to Earth’s magnetic field.
Earth’s Magnetic Field
Scientists think that Earth’s magnetic
field is produced by the movement of
electric charges in Earth’s core. The core is
mostly iron and nickel; the inner core is
solid because of the great pressure at that
level, but in the outer core, the metals are
liquid because there is less pressure. As
Earth rotates, the liquid in the core flows
and electric charges move, creating the
magnetic field. As the field travels outward
through the rest of Earth’s interior, the field
lines extend from Earth near Antarctica and
enter again near Canada.
Earth’s magnetic field acts like a giant
bar magnet. It has two poles—north and
south. When you put unlike poles together,
you can feel magnetic attraction. Like poles
of a bar magnet repel each other.
In the northern hemisphere, when a
compass needle points north, we use it as a
tool to find a direction. However, because
the north-pointing magnetism of the
compass needle can be attracted only by
the south pole of a magnet, the magnetic
pole in the northern hemisphere has a
south polarity. It follows that magnetic
north is at the geographic South Pole.
Going Home
Results of the lobster-behavior study
are illustrated below. Researchers moved
one group of lobsters (squares) from their
home at catch site 1 to the test site
southwest of their home. They moved
another group (circles) from their home at
catch site 2 to the test site that was
northeast of their home.
The lobsters were placed in opaque
containers and transported by boat along
circuitous routes of up to 30 km; then they
were released at the test site. The next day,
the lobsters were discovered positioned
facing the catch site and walking in the
direction indicated in the figure.
The researchers concluded that their
results demonstrated that an invertebrate
animal is capable of true navigation based
upon Earth’s magnetic field.
Applying Critical-Thinking Skills
Directions: Answer each question.
1.Relate Look up pictures of the Aurora Borealis (Northern Lights) and the Aurora
Australis (Southern Lights). What are they? Why do they occur?
2.Interpret In which directions were the CS1 and CS2 lobsters walking on the second
day of the lobster study?
20The Laws of Motion
Name Date Class
LESSON 1
Air Resistance by Design
Many common objects in daily use today were designed to increase or decrease air
resistance. Choose one of the following activities, A or B.
A.Model
1.Research the design, use, and construction of parachutes.
2.Diagram a common parachute design. Construct a full-sized model out of old
newspaper or other scrap material. Display the model in your classroom. Perhaps it can
hang from the ceiling.
3.Write a sentence or two describing the function a parachute serves for a parachutist.
B.Classify
1.On separate index cards or pieces of paper, diagram your observations of the design of
20 vehicles parked or traveling in the neighborhood of your home or school.
2.Group the diagrams into three different classifications, based on their shapes. Name
the three groups.
3.Write a sentence or two describing the relationship between the shape of a vehicle and
its performance.
The Laws of Motion21
Name Date Class
LESSON 1
Gravity and Friction
True or False
Directions: On the line before each statement, write T if the statement is true or F if the statement is false.
1.Gravity and magnetism are examples of contact forces.
2.Weight is the measure of gravitational force on an object.
3.Mass and weight are not related to each other.
4.Forces have strength and direction.
Multiple Choice
Directions: On the line before each question or statement, write the letter of the correct answer.
5.You can reduce friction by
A.increasing mass.
B.removing lubricant.
C.reducing surface area.
6.Which type of friction exists between a surface and moving air?
A.fluid friction
B.static friction
C.sliding friction
7.Which factor is NOT involved in determining gravitational force?
A.mass
B.speed
C.distance
8.A is NOT a force.
A.fall
B.pull
C.push
22The Laws of Motion
Name Date Class
LESSON 1
Gravity and Friction
Completion
Directions: On each line, write the term that correctly completes each sentence.
1.Gravity and magnetism are examples of forces.
2.is the measure of gravitational force on an object.
3.An object’s weight is proportional to its .
4.Forces have strength and .
Short Answer
Directions: Respond to each statement on the lines provided.
5.State two ways to reduce friction on an object.
6.Recall the three types of friction and explain how each acts on objects.
7.Assess what determines the strength of gravitational force between two objects.
8.Determine what is needed to exert a force.
The Laws of Motion 23