I.
Objectives
At the end of the lesson, the students should be able to:
1. Infer that when a body exerts a force on another, an equal amount of force is also exerted
back on it
2. Explain the phenomena behind the action and reaction forces and
3. Cite real life situation in which the third law of motion can be depicted.
II. Subject Matter
Topic: Newton’s third law: Law of Interaction
Approach: Constructivist
Materials: laptop, projector, white board, white board marker
Values Integration:
The students will see the importance of understanding the newton’s laws of
motion.
The students will appreciate the nature of laws and how it is apply in everyday
life.
References:
Exploring Life Through Science Second Edition
http://www.cpalms.org/Public/PreviewResourceLesson/Preview/35387
https://www.brighthubeducation.com/middle-school-science-lessons/35943-
newtons-third-law-of-motion/
III. Procedure
Teacher’s Activity Student’s Response
A. Preparatory Activity
Good Morning Class! Good Morning Ma’am.
I am Teacher Roan, and I will be your teacher
for today.
First, let us all stand up for a prayer.
Motivation
Before we start our proper discussion, let us
first have a game. The game will be called
Yes, No, Stand Up.
How to play:
1. Tell the students that answering “yes”
means stand up and answering “no”
means sit down.
2. Next, ask the students a few simple
questions to check that they
understand.
Do you like chocolate?
Do you like to run?
Is 2+2=5?
3. After the students understand, get a
stronger student to ask question.
There are three laws of motion. The first and
second laws were already discussed by
Madam and this lesson will focus on the third
law.
Let us first define the given words that you
will be using in this lesson.
Vocabulary
Ask the student to give the definition of the
given words:
Newton’s Third Law of Motion Students will define each term:
Force
Motion Force – A push or a pull.
Direction Motion – A change in position.
Direction – A course along which someone or
(Optional: have students write down the terms something moves.
and definitions in their science notebook) Newton’s Third Law of Motion - For every
action there is an equal and opposite re-
Presentation of New Lesson: action.
Our topic for today is about the Third Law
which is the Law of Interaction.
What does the Newton’s third law of motion
states?
According to Newton's third law...
“For every action there is an equal and
opposite reaction.”
What does this mean? Ask a student
( When you push an object, it pushes back) This means that for every force there is a
reaction force that is equal in size, but
opposite in direction. That is to say that
whenever an object pushes another object it
gets pushed back in the opposite direction
equally hard.
Read the information as a class.
Newton's third law of motion - For every
action there is an equal and opposite re-
action.
I will be presenting to you a short video that
will show you clearly the forces action and
reaction in law of interaction.
(Video Presentation)
Class, remember that third law states that
“when a body A exerts a force on body B,
body B will exert an equal or oppositely
directed force on body A.” that is what it
meant when they said that “to every action,
there is an equal but opposite reaction force.”
For Example, If I touch the table of course my
hand exerted a force upon the table; does the
table also exert a force on my hand? Yes, teacher
Asked a student: How much the force did the
table exert? Equivalent to the force applied by your hand
teacher!
Very good! That is how the third law of
motion works. You cannot touch without
being touched.
If you push hard on a wall with by a force of
5 N, the wall it turns pushes you back by a
force of 5 N.
Another popular example of the third law of
motion is the Horse cart paradox. Have you
heard it before class?
Before I tell you the story, I have a question.
Based on the given definition and example of
the third law of motion; the law of interaction,
do action and reaction cancel out each other?
( the students will give their varied opinions
about the question)
Well, let me tell you the story, one morning, a
trainer and his horse were having an
argument. The horse that happens to know a
little physics told his trainer that it is useless
for the former to pull the cart. The harder the
horse pulls the cart, the harder the cart pulls
back on him. These forces will cancel each
other, and the net forces will be zero in as
much as action and reaction are supposed to
be equal but opposite direction. The horse
further said that since there is no net force,
then the cart will remain at rest in accordance
with Newton’s first law.
Now if you are the trainer, will you agree
with the horse? ( the students will give their varied opinions
about the question)
Of the two forces mentioned by the horse, it is
only the force that the horse exerts on the cart
that is acting on the cart. The other force in
the action-reaction force is acting on the horse
and not on the cart. Since action and reaction
forces are acting on two different objects,
they will never be cancelled out. The cart will
accelerate if the forces exerted by the horse
on the cart is greater that the force of the
friction between the cart and the ground.
Generalization
Now, go back to the question earlier, do
action and reaction forces cancel out each No, action and reaction forces are acting on
other? different bodies therefore, they will never
cancel out each other.
In every action, there is an equal but opposite
reaction forces.
Action and reaction forces are equal in
magnitude but oppositely directed.
Action and reaction forces are acting on
different bodies will never cancel out.
Forces always come in pairs.
IV. Activity (Independent Practice)
Answer the following scenarios. Include examples and specific details in your answers.
a. How does Newton's third law of motion explain how we walk?
b. When a man jumps out of a boat to the bank of river.
Answer:
a. We can walk because we push backward upon on Earth as hard as the Earth pushes us
forward. When you put your foot on the ground, you are applying a force to it. In doing this, the
ground also actually applies an equal force onto your foot, in the opposite direction, pushing you
forward.
b. When a man jumps out of a boat to the bank of river, the boat moves backwards
because the man pushes the boat with his foot in backward direction and boat exerts equal force
on man in forward direction which enables him to move forward.
V. Evaluation
Find a partner. Find out five or more examples of Newton’s third law motion from our day to
day life. Write down the action and reaction on them. Be creative in choosing your examples and
should not be any of the same already discussed.
Afterwards each group will share their examples and explain it in the class.
Example student responses could include:
a. A person pushing a skateboard with their foot.
b. An archer shooting an arrow at a target.
c. A hockey player slapping the puck toward the goal.
Learning Goals: Students will be able to explain what happens when a force is applied to an
object, but it does not move.
Score 4 The student demonstrates understanding beyond what was taught in the unit, such as:
Connecting Newton’s third law of motion to real life events.
Demonstrating various examples of Newton’s third law of motion.
No major errors with Score 4 content
Score 3 The student explains Newton’s third law of motion while correctly relating the law to
various aspects of the assessment.
Score 4 The student demonstrates understanding beyond what was taught in the unit, such as:
Connecting Newton’s third law of motion to real life events.
Demonstrating various examples of Newton’s third law of motion.
No major errors with Score 4 content
No major errors with Score 3 content
Score 2 The student demonstrates understanding of the simpler content, such as:
For every action, there is a reaction.
Sometimes equal, opposite forces causes no change in motion.
No major errors with Score 2 content
Score 1 With help, the student demonstrates some success with Score 2 content and Score 3
content.
Score 0 Even with help, the student demonstrates no success.
