THIRD LAW OF MOTION
Topic: Law of Action Reaction
I. Previous knowledge
 First law of motion - Law of Inertia
 Second law of motion - Law of Force
II. Objectives
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explain Newton's third law of motion
identify the action and reaction in forces
A. Length - 60 Mins.
B. Source - https://www.youtube.com/watch?v=Mb8IWtOX2fs
III. Engage

Ask questions to the students according to the previous topic.
(What is inertia? - Inertia is the idea that an object will continue its current motion until
some force causes its speed or direction to change.)
(What can a force change? - Speed)
(State the second law of motion - The acceleration of an object depends on the mass of
the object and the amount of force applied.
Now moving on to the next topic,
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Show a video on YouTube about Action Reaction: Newton’s Third Law
IV. Explore
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Perform an activity. Take a rubber ball and throw it towards the wall.
Let the students take down their observations.
Ask the students what they observed.
(What happened to the ball after it was stroked on the wall? - The ball bounced back
after it was strike on the wall)
(Why did the ball bounced back? - The ball bounced back due to the force exerted when
it hit the wall.)
V. Explain
 Explain the third law of motion on the basis of observation from the activities
performed.
Newton’s third law of motion states that every action has an equal and opposite reaction.
It means that in every interaction, there is a pair of forces acting upon the interacting
objects.
The magnitude of forces are equal and the direction of the force on the first object is
opposite to the direction of the force of the second object.
For example: Release of air-filled balloon
Action - Release of air in downward direction
Reaction - Balloon moves in upward direction
VI. Elaborate
 Give some illustrations regarding Newton’s third law of motion and ask for their
explanations.
Example: Firing a bullet from a gun - When firing a bullet, the bullet accelerates in
forward direction and exerts the same force in backward direction on the gun.
VII. Evaluate
 Give some examples for Newton’s third law of motion.
 Why do we get hurt when we kick the wall?