8
Science 8
Quarter 1 – Module 2:
Action-Reaction
(Week 2/Day 1-3)
Science 8
Self-Learning Module (SLM)
Quarter 1 – Module 2: Action-Reaction
First Edition, 2020
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over them.
Development Team of the Module
Writers: Geraldine C. Toledo
Editors: Sally A. Palomo
Reviewers: Sally A. Palomo, Nerissa A. Alfafara
Illustrator: Geraldine C. Toledo / Trixie Jen S. Cañete
Layout Artist: Geraldine C. Toledo
Cover Art Designer: Reggie D. Galindez
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Mario M. Bermudez, CESO VI – Assist. Schools Division Superintendent
Gilbert B. Barrera – Chief, CLMD
Arturo D. Tingson Jr. – REPS, LRMS
Peter Van C. Ang-ug – REPS, ADM
Peter Van C. Ang-ug – REPS, Science
Juliet F. Lastimosa - CID Chief
Sally A. Palomo - Division EPS In- Charge of LRMS
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Science 8
Quarter 1 – Module 2:
Action-Reaction
(Week 2/Day 1-3)
Introductory Message
For the facilitator:
Welcome to the Science 8 Self-Learning Module (SLM) on Action-Reaction!
This module was collaboratively designed, developed and reviewed by educators both
from public and private institutions to assist you, the teacher or facilitator in helping
the learners meet the standards set by the K to 12 Curriculum while overcoming
their personal, social, and economic constraints in schooling.
This learning resource hopes to engage the learners into guided and independent
learning activities at their own pace and time. Furthermore, this also aims to help
learners acquire the needed 21st century skills while taking into consideration their
needs and circumstances.
In addition to the material in the main text, you will also see this box in the body of
the module:
Notes to the Teacher
This contains helpful tips or strategies that
will help you in guiding the learners.
As a facilitator you are expected to orient the learners on how to use this module.
You also need to keep track of the learners' progress while allowing them to manage
their own learning. Furthermore, you are expected to encourage and assist the
learners as they do the tasks included in the module.
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For the learner:
Welcome to the Science 8 Self-Learning Module (SLM) on Action-Reaction!
The hand is one of the most symbolized part of the human body. It is often used to
depict skill, action and purpose. Through our hands we may learn, create and
accomplish. Hence, the hand in this learning resource signifies that you as a learner
is capable and empowered to successfully achieve the relevant competencies and
skills at your own pace and time. Your academic success lies in your own hands!
This module was designed to provide you with fun and meaningful opportunities for
guided and independent learning at your own pace and time. You will be enabled to
process the contents of the learning resource while being an active learner.
This module has the following parts and corresponding icons:
What I Need to Know
This will give you an idea of the skills or
competencies you are expected to learn in the
module.
What I Know
This part includes an activity that aims to
check what you already know about the
lesson to take. If you get all the answers
correct (100%), you may decide to skip this
module.
What’s In
This is a brief drill or review to help you link
the current lesson with the previous one.
What’s New
In this portion, the new lesson will be
introduced to you in various ways such as a
story, a song, a poem, a problem opener, an
activity or a situation.
What is It
This section provides a brief discussion of the
lesson. This aims to help you discover and
understand new concepts and skills.
What’s More
This comprises activities for independent
practice to solidify your understanding and
skills of the topic. You may check the
answers to the exercises using the Answer
Key at the end of the module.
What I Have Learned
This
includes
questions
or
blank
sentence/paragraph to be filled in to process
what you learned from the lesson.
What I Can Do
This section provides an activity which will
help you transfer your new knowledge or skill
into real life situations or concerns.
Assessment
This is a task which aims to evaluate your
level of mastery in achieving the learning
competency.
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Additional Activities
In this portion, another activity will be given
to you to enrich your knowledge or skill of the
lesson learned. This also tends retention of
learned concepts.
Answer Key
This contains answers to all activities in the
module.
At the end of this module you will also find:
References
This is a list of all sources used in developing
this module.
The following are some reminders in using this module:
1. Use the module with care. Do not put unnecessary mark/s on any part of the
module. Use a separate sheet of paper in answering the exercises.
2. Don’t forget to answer What I Know before moving on to the other activities
included in the module.
3. Read the instruction carefully before doing each task.
4. Observe honesty and integrity in doing the tasks and checking your answers.
5. Finish the task at hand before proceeding to the next.
6. Return this module to your teacher/facilitator once you are through with it.
If you encounter any difficulty in answering the tasks in this module, do not
hesitate to consult your teacher or facilitator. Always bear in mind that you are
not alone.
We hope that through this material, you will experience meaningful learning and
gain deep understanding of the relevant competencies. You can do it!
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What I Need to Know
This module was designed and written with you in mind. It is here to help you
master the concept of Action-Reaction. The scope of this module permits it to be used
in many different learning situations. The language used recognizes the diverse
vocabulary level of students. The lessons are arranged to follow the standard
sequence of the course. But the order in which you read them can be changed to
correspond with the textbook you are now using.
After going through this module, you are expected to:
• to infer that when a body exerts a force on another, an equal amount
of force is exerted back on it (S8FE-Ia-16).
And, specifically you are to:
1. state the third law of motion;
2. identify action-reaction force pairs; and
infer that when a body exerts a force on another, an equal amount of force is
exerted back on it.
What I Know
Before you begin exploring, test yourself to check your stock knowledge regarding
the topic to be discussed in this learning material.
Choose which you think is the correct answer and write the chosen letter on a
separate sheet of paper. Enjoy reading and answering!
1. According to Newton’s third law of motion, when a rock strikes and exerts
force on a nail, the nail _________________.
A. creates a tension with the rock
B. exerts an equal force back on the rock
C. will disappear
D. will be transferred to another wood
2. Newton's third law of motion states that whenever one object exerts a force on
a second object, _________________.
A. the second object exerts an equal and opposite force on a third object
B. the first object is not affected by that force
C. the second object exerts an equal and opposite force on the first object
D. the second object exerts a less powerful force on the first object
3. When a swimmer swims through water, _________________
A. the reaction force is what moves the swimmer forward.
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B. the action force could be the swimmer's hands and feet pushing on the
water.
C. the reaction force could be the water pushing on the hands and feet.
D. All the above
4. Action and reaction force pairs occur _________________
A. only when there is motion.
B. whether there is motion or not.
C. only when there is no motion
D. only when the forces are unbalanced.
5. In an action-reaction situation, ______________________.
A. the forces are cancelled.
B. the forces are not cancelled.
C. the force is doubled.
D. the reaction force is less than the action force.
6. Which statement is NOT true about action and reaction forces?
A. Reaction always equals action.
B. The magnitude of the reaction force is greater than the action force
C. The reaction force is in the opposite direction of the action force
D. The reaction and action forces are the equal in magnitude
7.
A jeepney hits a firefly and the firefly splatters on the windshield, which force
is greater?
A. the jeepney
B. the firefly
C. they're the same
D. gravity acting on the jeepney
8.
When Manny Pacquiao punch his opponent with a left hook, what is the
interaction pair?
A. The foot and the face
B. The fist and the face
C. The face and the arm
D. The arm and the head
9.
Newton's third law states that any action will have a(n) _______ and ______
reaction
A. Equal and the same
B. Greater and opposite
C. Equal and different
D. Equal and opposite
10.
You hit a bamboo fence with a broomstick. The equal but opposite reaction
is _________________
A. the wall pushes against the broomstick
B. the bamboo fence pushes against you
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C. the broomstick pushes against you
D. you push against the broomstick
11. Whenever an object exerts a force on another object, the second object exerts
a force of the same magnitude, but in the opposite direction to that of the
first object. The statement is ________________.
A. Never true
B. Always true
C. Sometimes true
D. Always false
12. A junior high school student hits a pole with a hammer. During the collision,
there is a force_________________
A. on the hammer but not on the pole.
B. on the pole but not on the hammer.
C. on the pole and also on the hammer.
D. None of the above
13. If a carabao pulls on a wagon that is not moving, the wagon pulls back
equally as much on the carabao. Will the wagon be set into motion?
A. Yes, because there is a net force acting on the wagon.
B. Yes, because there is enough time interval between action and reaction.
C. Yes, because the carabao’s pull on the wagon is larger than the wagon’s
pull on the horse.
D. No, because the forces cancel each other.
14. Consider a bullet shot from a gun. The acceleration of the bullet is _____.
A. greater than the acceleration of the gun.
B. equal to the acceleration of the gun.
C. equal but opposite to the acceleration of the gun.
D. less than the acceleration of the gun.
15. Consider a frog swimming forward in the pond. Which of the following
describes the basic action/reaction forces between the frog and the water?
A. The force of the frog’s swimming and the force of the water are equal
but in opposite directions.
B. The only force is the activity of the frog moving forward.
C. The force of the frog points upward while the force of the water pulls
downward.
D. The forces point in the same direction because forces in liquid media
behave differently than forces in air.
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Lesson
2
Physics: Action-Reaction
You probably know that when you walk or run, you are exerting force on the
ground by stepping on it but what you didn’t realize, the ground is also pushing you
upward. Example, if you are exerting 10 units of force when you step on the ground,
the ground also exerts 10 units of force upward. This may sound unbelievable, but
this astonishing fact is the consequence of Newton’s Third Law of Motion, the Law of
Interaction.
As you go through this learning material, you will be able to learn more of
Isaac Newton’s Law of Interaction.
What’s In
In your previous lesson, you have learned that different objects have different
amount of inertia, the tendency of an object to resist a change in position, and the
inertia of an object depends on its mass. Thus, the heavier the object, the greater the
force is needed to change its motion or position. The change in an object’s motion or
velocity over a period of time is referred to as acceleration, therefore, the greater the
force applied to an object, the greater the acceleration.
You also have learned that a net force is produced when two interacting
objects produced an unbalanced force and the direction of the object’s acceleration
follows the direction of the net force. This gives us the concept of the second law of
motion, the Law of Acceleration, which states that acceleration is directly
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proportional to the force but inversely proportional to the mass of the object. This can
be expressed in this equation: a = F/m.
To help you remember the lessons you have learned previously, try the activity
below.
Tickle your mind and remember the past!
For you to know what you have acquired in your previous lesson, look at the
illustration and try answering the questions below.
1.
2.
3.
4.
Draw a solid arrow to show the direction of the velocity.
Is a force acting upon the object?
Is the object accelerating?
If accelerating, draw a dotted arrow to indicate the direction of the
acceleration (change in velocity).
Heads Up!
Isaac Newton discovered the laws of motion such as the law of
inertia, law of acceleration, and the last one is the law of interaction
which states that in every action, there is an equal but opposite reaction,
giving us the concept of Action-Reaction forces which will be understood
well as you go through this learning material.
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What’s New
A bamboo cannon is a type of a home-made firecracker which is popular
during New Year's Eve celebrations in the Philippines. Many Filipinos use "Kerosene
Bamboo Cannons" as an alternative to firecrackers, during Christmas and New Year
celebration.
It was said that Bamboo Cannons were introduced to the Filipinos by Chinese
traders as weapons, even before the Spanish colonizers arrived on the shores of the
Philippine Archipelago.
Your parents might have experienced using Bamboo Cannons during their
younger years. Ask them about it. You may ask them with the following guide
questions:
1.
2.
3.
4.
5.
6.
7.
Have you tried using Bamboo Cannons?
How did you make it?
How was your experience?
How do you fire it?
What happens when it fires?
How about the bamboo, what happens to the bamboo when it fires?
Does the bamboo recoil when it fires?
Take note!
After getting the answers to the given questions, you should be able to learn
that when bamboo cannon fires, it recoils. It means that when it releases gas forward,
the bamboo moves backward. This concept is very important because this says a lot
regarding Newton’s third law of motion which will be the focus of learning of this
module.
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What is It
Basketball is one of the major sports in
the Philippines. The purpose of this sport is to
score more points than the other team before
time runs out.
In this game, a player must be able to
dribble the ball to get to their assigned court
and shoot the ball in the basket to get a point.
Points are given for each made basket. A player
who will fail to dribble the ball while going to
their court will be called for violation and the
ball will be given to the opposite team.
Now observe what happens during the
dribbling of the ball. When the ball is pushed
downwards, the ball bounces upward. This
would tell us that an opposing force makes the
ball to move in the opposite direction. This is
the concept of the third law of motion.
The ball is
pushed
downwards
The ball bounces upward
The Newton’s third law of motion is known as the Law of Interaction. It
states that for every action force there is an equal (in magnitude) and opposite (in
direction) reaction force.
Thus, if object A exerts a force on object B, then object B must exert a force of
equal magnitude and opposite direction back on object A.
Object A
– Book
Object A – Hammer
Object B
– Book
Object B - Nail
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Moreover, no force exists alone, it always comes in pairs. This pair is known
as "action-reaction force pair." Identifying and describing action-reaction force
pairs is just a matter of identifying the two interacting objects and making two
statements describing who or which is pushing on whom or which and in what
direction.
In the illustration below, the force applied on hammering of the nail downward
is the action force while the force of the nail that pushes the hammer which causes
it to bounce back is the reaction force.
Action Force
➢ The hammer pushes the nail downward.
Reaction Force
➢ The nail pushes the
hammer upwards.
However, the idea of equal magnitude may seem to be confusing because it
seems to imply that forces are balanced so the object will not move. Let it be cleared
that this idea is incorrect.
Even though the forces are equal in magnitude and opposite in direction, they
do not cancel each other because action-reaction forces act on different objects and
it is only focused in an isolated system. The system refers to the pair of actionreaction forces.
In the illustration given, the systems may be the forces acting on the hammer
or the forces acting on the nail. Thus, if you are looking at the nail, consider only the
forces acting on the nail, and if you are looking at the hammer, consider only the
forces acting on the hammer. You must understand that the concept of actionreaction forces lies within an isolated system. Meaning, the pair of forces is not
affected by any pairs of force observed in a given situation.
To understand more about the different systems or pair of action-reaction
forces in a certain situation, consider the illustration where a skater is pushing the
skateboard to move forward. Take note that as the skater pushes the ground
backward, the skater moves forward. This is an explicit illustration of the actionreaction forces. Here, the action force would be the pushing of the ground while the
reaction force would be ground pushing the skater to move forward.
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As you can see, there are more than two systems or pairs of action-reaction
forces that can be identified in the illustration above but let us just consider isolating
two systems here. We have:
System A
➢ Action Force: the gravity is pulling the skater downward
➢ Reaction Force: the ground pushing the skater upward
System B
➢ Action Force: the skater pushes ground backward
➢ Reaction Force: the ground pushes the skater to move forward
In learning to isolate systems or pair of action-reaction forces, you will be able
to understand that forces in a system do not cancel each other because they are not
affected by the forces of the other systems in a given situation. But why does the
skater move? It is because a net force is acting on these systems. It may mean that
System B has greater force than that of System A. Thus, the direction of the object
follows the direction of the net force.
Example:
System B (20 N)
System A (10 N)
Net Force =
System B (10 N)
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Take note!
You must always consider that for every action force there is an equal (in
magnitude) and opposite (in direction) reaction force. Thus, if object A exerts a force
on object B, then object B must exert a force of equal magnitude and opposite
direction back on object A
Take note that no force exists alone, it always comes in pairs. This pair is
known as "action-reaction force pair." Identifying and describing action-reaction
force pairs is just a matter of identifying the two interacting objects and making two
statements describing who or which is pushing on whom or which and in what
direction.
Consider also that action-reaction forces do not cancel each other because
they act on different objects and when the object moves, it is because the net force
is acting on it.
Let us find out if you were able to grasp the concept of the Third Law of Motion.
Challenge yourself by answering the following activities.
What’s More
Activity 1.1 Understanding the Law of Interaction
Analyze the illustrations below and answer the given questions.
A. Deflating Balloon
1. What is the direction of the air when
the balloon deflates?
_____________________________________
_____________________________________
2. What is the direction of the balloon
when it deflates?
_____________________________________
_____________________________________
3. Is there a force observed in the
illustration? If yes, which one is
exerting the force?
_____________________________________
_____________________________________
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B. Frog swimming in the pond
1. What is the direction of the frog as it
swims?
_____________________________________
_____________________________________
2. What causes it to move towards that
direction?
_____________________________________
_____________________________________
3. Is there a force observed in the
illustration? If yes, which one is
exerting the force?
_____________________________________
_____________________________________
C. What can you say about the forces exerted by the objects and the direction of
the object’s motion?
__________________________________________________________________________________
__________________________________________________________________________________
Take note!
In this activity, you must be able to learn that for every action there is always
an opposite reaction. This “opposite reaction” refers the direction of the force acting
on the objects. Try the next activity to learn more on the magnitude of the forces
acting on or exerted by the objects.
Activity 1.2 Action-Reaction
Objective:
• In this activity, you should be able to state Newton’s Third Law of Motion.
Materials:
• 2 spring balances
• String
Procedure:
1. Connect 2 spring balances with their hooks. Ask your partner to hold one
end of the balance while you hold the other end horizontally. Pull the spring
balance while your partner just holds the other end. Record the reading on
each balance.
Q1. What is the reading on your balance and that of your partner? What do
these values represent?
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
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Q2. How do you compare the direction of your partner’s and your force?
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
2. Pull the spring balance harder. Be careful not to exceed the maximum
reading on the spring balance.
Q3. What is the reading on your balance and that of your partner?
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
Q4. How do you explain your observation?
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
3. Attach one end of your spring balance to the wall, while the other end is
connected to the second spring balance. Ask your partner to pull the spring
balance. Observe the reading on each balance.
Q5. What is the reading in each balance?
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
Q6. Compare the direction of the forces exerted on the two ends of the
connected spring balance.
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
Take note!
After performing this activity, you should be able to learn that for every action,
there is always an equal reaction. The “equal reaction” refers to the magnitude of
the force exerted by an object. Meaning, if object A exerts 10 units of force to object
B, object B also exerts 10 units of force to object A.
Since you now have the idea on the action-reaction forces, challenge yourself
to apply your learnings by answering the next activity.
Tip: It states that for every action force there is an equal (in magnitude) and opposite
(in direction) reaction force.
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Activity 1.3 Action-Reaction Pair
Check your learnings on Action-Reaction Force Pair. Look at the illustrations
below and identify the pair of action-reaction forces.
I. Observe what is going on in the illustrations provided and
answers the given questions.
A. A baseball bat
hits a ball.
1. What happens to the ball?
2. What happens to the baseball bat?
3. What is the ACTION force?
4. What is the REACTION force?
5. Label the direction of the action and reaction forces by drawing an arrow on
the illustration.
B. Sepak Takraw
Player kicks the
ball forward.
1. What happens to the Sepak ball?
2. What happens to the foot?
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3. What is the ACTION force?
4. What is the REACTION force?
5. Label the direction of the action and reaction forces by drawing an arrow on
the illustration.
II. In this part, identify at least six pairs of action-reaction force
pairs in the in the illustration below.
1
2
3
What is the
ACTION force?
What is the
REACTION force?
What is the
ACTION force?
What is the
REACTION force?
What is the
ACTION force?
What is the
REACTION force?
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4
5
6
What is the
ACTION force?
What is the
REACTION force?
What is the
ACTION force?
What is the
REACTION force?
What is the
ACTION force?
What is the
REACTION force?
Take note
In this activity, you must be able to infer that when a body exerts a force on
another, an equal amount of force is exerted back on it. You must also be able to
identify pairs of action-reaction forces.
For you to be reminded of the concepts discussed in this learning material,
the following portion will help you sum up all the concepts presented.
Remember These…
➢ Newton's third law states that for every action force there is an equal (in
magnitude) and opposite (in direction) reaction force.
➢ No force exists alone, it always comes in pairs - known as "action-reaction
force pairs."
➢ Identifying and describing action-reaction force pairs is a simple matter of
identifying the two interacting objects and making two statements describing
who or which is pushing on whom or which and in what direction.
➢ Action and reaction have same magnitude.
➢ Action and reaction are opposite in direction.
➢ Action and reaction work on two different bodies.
➢ Action and reaction work simultaneously.
➢ Action and reaction do not cancel each other.
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What I Have Learned
Let’s see what you have learned about the Law of Interaction. Below are
statements which might be CORRECT or INCORRECT regarding the concept of
action-reaction force pair. Draw an arrow pointing to the right
if statement
is correct and an arrow pointing to the left
if the statement is incorrect.
CORRECT or INCORRECT?
1.
Newton's third law states that for every action force there is an
equal and opposite reaction force.
2.
Forces always come in pairs known as "action-reaction force
pairs."
3.
Action and reaction do have same magnitude and direction.
4.
If an object A exerts a force on object B, then object B must
exert a force of equal magnitude and opposite direction back
on object A.
5.
Action and reaction work on the same bodies.
6.
Action and reaction forces cancel each other
7.
Action and reaction work simultaneously.
8.
Action and reaction force pairs occur only when the forces are
unbalanced.
9.
Action and reaction force pairs occur only when there is
motion.
10.
Action and reaction are the same in direction.
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What do
you think?
What I Can Do
Now that you have already learned the concept of action-reaction forces, apply what
you have learned by answering the questions on the next page.
Photo from Levie T. Tulingin
The picture was taken at Purok Saeg, Barangay Calumpang of General Santos City,
where small fishing vessels dock. Even at young age, people in this area are skilled in fishing
using small boats and paddles.
Assuming that the boy in the picture wants to move the boat backward:
1. In what direction would the movement of the paddle must be? Why?
___________________________________________________________________________________
___________________________________________________________________________________
___________________________________________________________________________________
2. Will the Law of interaction be applied in this situation? Explain your answer.
___________________________________________________________________________________
___________________________________________________________________________________
___________________________________________________________________________________
3. What is the action force?
___________________________________________________________________________________
___________________________________________________________________________________
4. What is the reaction force?
___________________________________________________________________________________
___________________________________________________________________________________
5. State the Law of Interaction.
___________________________________________________________________________________
___________________________________________________________________________________
___________________________________________________________________________________
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Assessment
Let’s check your learnings! Now that you already grasped all the essential of
action-reaction forces, try answering the following questions to know have far have
you gone.
Choose the letter of the best answer and write the chosen letter on a separate
sheet of paper.
Enjoy answering!
1. According to Newton’s third law of motion, when a rock strikes and exerts
force on a nail, the nail _________________
A. creates a tension with the rock.
B. exerts an equal force back on the rock.
C. Will disappear.
D. will be transferred to another wood.
2. Newton's third law of motion states that whenever one object exerts a force on
a second object, _________________
A. the second object exerts an equal and opposite force on a third object.
B. the first object is not affected by that force.
C. the second object exerts an equal and opposite force on the first object.
D. the second object exerts a less powerful force on the first object.
3. When a swimmer swims through water, _________________
A. the action force could be the swimmer's hands and feet pushing on the
water.
B. the reaction force is what moves the swimmer forward.
C. the reaction force could be the water pushing on the hands and feet.
D. All of the above
4. Action and reaction force pairs occur _________________
A. only when there is no motion
B. only when there is motion.
C. whether there is motion or not.
D. only when the forces are unbalanced.
5. In an action-reaction situation, ______________________.
A. the force is doubled.
B. the reaction force is less than the action force.
C. the forces are cancelled.
D. the forces are not cancelled.
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6. Which statement is NOT true about action and reaction forces?
A. The reaction and action forces are the equal in magnitude
B. Reaction always equals action.
C. The magnitude of the reaction force is greater than the action force
D. The reaction force is in the opposite direction of the action force
7.
A jeepney hits a firefly and the firefly splatters on the windshield, which force
is greater?
A. gravity acting on the jeepney
B. the jeepney
C. the firefly
D. they're the same
8.
When Manny Pacquiao punch his opponent with a left hook, what is the
interaction pair?
A. The fist and the face
B. The foot and the face
C. The face and the arm
D. The arm and the head
9.
Newton's third law states that any action will have a(n) _______ and ______
reaction
A. Equal and opposite
B. Equal and the same
C. Equal and different
D. Greater and opposite
10.
You hit a bamboo fence with a broomstick. The equal but opposite reaction
is _________________
A. the broomstick pushes against you
B. you push against the broomstick
C. the wall pushes against the broomstick
D. the bamboo fence pushes against you
11. Whenever an object exerts a force on another object, the second object exerts
a force of the same magnitude, but in the opposite direction to that of the
first object. The statement is ________________.
A. Always false
B. Never true
C. Sometimes true
D. Always true
12. A junior high school student hits a pole with a hammer. During the collision,
there is a force_________________
A. on the pole and on the hammer.
B. on the hammer but not on the pole.
C. on the pole but not on the hammer.
D. None of the above
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13. If a carabao pulls on a wagon that is not moving, the wagon pulls back
equally as much on the carabao. Will the wagon be set into motion?
A. No, because the forces cancel each other.
B. Yes, because the carabao’s pull on the wagon is larger than the wagon’s
pull on the horse.
C. Yes, because there is a net force acting on the wagon.
D. Yes, because there is enough time interval between action and reaction.
14. Consider a bullet shot from a gun. The acceleration of the bullet is _____.
A. equal to the acceleration of the gun.
B. equal but opposite to the acceleration of the gun.
C. greater than the acceleration of the gun.
D. less than the acceleration of the gun.
15. Consider a frog swimming forward in the pond. Which of the following
describes the basic action/reaction forces between the frog and the water?
A. The forces point in the same direction because forces in liquid media
behave differently than forces in air.
B. The force of the frog’s swimming and the force of the water are equal
but in opposite directions.
C. The only force is the activity of the frog moving forward.
D. The force of the frog points upward while the force of the water pulls
downward.
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Additional Activities
Challenge yourself!
While driving down the road, a firefly strikes the windshield of a bus and
makes a quite obvious mess in front of the face of the driver. This is a clear case of
Newton’s third law of motion. The firefly hit the bus and the bus hits the firefly.
Tip: Use your learning on the Laws of Motion in answering the problem.
When unfortunate firefly splatters against the windshield of a moving bus,
why did the bus continue moving if the amount of force is equal?
__________________________________________________________________________________
__________________________________________________________________________________
__________________________________________________________________________________
__________________________________________________________________________________
__________________________________________________________________________________
__________________________________________________________________________________
__________________________________________________________________________________
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Activity 1.1
Activity 1.2
Activity 1.3
What’s More
What’s More
What’s More
A. Baseball
1. hit by bat
forward
2. hit by the ball
backward
3. the bat hitting
the ball
forward
4. the ball hitting
the bat
backward
Q1.
Q2.
Q3.
5.
Q4.
Q5.
Q6.
Answer may differ, but
the values should be
equal. These values
represent the amount
of pulling force that we
exerted on each other.
The forces that we
exerted are in opposite
directions.
The readings this time
should be greater than
the previous ones.
We increased the force
that we exerted on
each other.
Readings may vary
The forces are of
opposite directions.
What’s In
What’s New
Answers must
come from the
person being
asked.
1.
The learners
must be able to
realize that as
Bamboo cannon
fires, it recoils.
2. Yes
3. Yes
This will allow
the learners to
be introduced
with the concept
of the 3rd law of
motion.
4.
A. Balloon
6. to the right
7. to the left
8. Yes, the
balloon and
the air
B. Frog
1. forward
2. The pushing
frog kick to
backward
3. Yes, the frog
and the water
C. Both objects
exert forces in
opposite
direction.
What I know
1. B
2. C
3. A
4. B
5. B
6. B
7. C
8. B
9. D
10. A
11. B
12. C
13. A
14. A
15. A
Answer Key
27
What I Have
Learned
What Can I Do
1. The direction of the paddle must
be forward
1.
2.
2. Yes, the force exerted to move
the boat backward is by
paddling in forward direction.
3.
4.
5.
3. Paddling in forward direction
4. The boat
backward
that
is
6.
moving
7.
8.
5. In every action, there is an equal
and opposite reaction.
9.
10.
What’s More
What’s More
Activity 1.3
Activity 1.3
B. Sepak Takraw
C. Action Reaction Force Pairs
1. Action: the wheel pushing the ground downward
Reaction: the ground pushing the wheel upward
1. kicked by foot
forward
2. hit by the ball
backward
3. the foot
kicking the
ball forward
4. the ball hitting
the foot
backward
2. Action: the carabao pushing the ground downward
Reaction: the ground pushing the carabao upward
3. Action: the carabao pulling the card forward
Reaction: the cart pulling the carabao backward
4. Action: the sack is pushing the other sack downward
Reaction: the sack below is pushing the other sack
upward
5.
5. Action: the rope is pulling the card forward
Reaction: the cart is pulling the rope backward
6. Action: the stone pushing the ground downward
Reaction: the ground pushing the stone upward
Note: There are more than six action-reaction forces
observed in the illustration, consider the answer of the
learners as long as it is correct.
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Assessment
Additional Activities
Each force is of equal size. Take note that the
3rd law of motion states that for every action,
there is an equal and opposite reaction.
The fact that the firefly splatters only means
that with its smaller mass, it is less able to
withstand the larger acceleration resulting
from the interaction.
Thus, the law of acceleration applies when we
talk of the motion of the object. Force is just
part of it, the other one is the mass of the
objects. These quantities play important roles
in determining the acceleration of the object.
1. B
2. C
3. B
4. C
5. D
6. C
7. D
8. A
9. A
10. C
11. D
12. A
13. C
14. C
15. B
References
Book Sources:
DepEd Learning Module in Grade Eight Science
DepEd K to 12 Science Curriculum Guide
Ferando MA. Duran Nolasco, Yolanda I. Lomotan, Manuela P. Pagunsan,
Purita R. Martin, Physics 4, Salesiana Publishers, Inc. 2005
Joanna M. Abistado, Maliza P. Valdoz, Jan Jason M. Mariano, Science Links
7, Rex Bookstore, 2013
Lilia G. Vengco, Teresita F. Religioso, Integrated Science, Phoenix Publishing
House, 2008
John Paolo C. Dalupang, Marianne V. Bagunu. Meliza P. Valdoz, Science
Links – Integrated Science, Rex Bookstore, 2012
Online Sources:
https://www.guaduabamboo.com/uses/lantaka-kerosene-bamboo-cannons
https://www.teachengineering.org/lessons/view/ucd_newton_lesson03
http://www.mayfieldschools.org/Downloads/Worksheet%202_Newton's%20
3rd%20Law.pdf
https://www.physicsclassroom.com/class/newtlaws/Lesson-4/IdentifyingAction-and-Reaction-Force-Pairs
https://www.teachengineering.org/content/ucd_/lessons/ucd_newton/ucd_
newton_lesson03_presentation_v2_tedl_dwc.pdf
https://www.quora.com/What-are-some-examples-of-the-third-law-ofmotion\
https://www.khanacademy.org/science/physics/forces-newtonslaws/newtons-laws-of-motion/a/what-is-newtons-third-law
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DISCLAIMER
This Self-learning Module (SLM) was developed by DepEd SOCCSKSARGEN
with the primary objective of preparing for and addressing the new normal.
Contents of this module were based on DepEd’s Most Essential Learning
Competencies (MELC). This is a supplementary material to be used by all
learners of Region XII in all public schools beginning SY 2020-2021. The
process of LR development was observed in the production of this module.
This is version 1.0. We highly encourage feedback, comments, and
recommendations.
For inquiries or feedback, please write or call:
Department of Education – SOCCSKSARGEN
Learning Resource Management System (LRMS)
Regional Center, Brgy. Carpenter Hill, City of Koronadal
Telefax No.: (083) 2288825/ (083) 2281893
Email Address: region12@deped.gov.ph
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