This document outlines a 45 minute physics lesson plan for 9th standard students on Newton's third law of motion and conservation of momentum. The lesson uses presentations, activities, and sample problems to help students understand key concepts. Students view presentations on examples of Newton's third law like a tea bag rocket. They analyze experiments showing conservation of momentum with moving balls. They also solve a sample problem calculating momentum before and after a gun is fired. The goal is for students to grasp that for every action there is an equal and opposite reaction, and that the total momentum of a system remains constant.

1. PRESENTED BY
RENJINI R
PHYSICAL SCIENCE
MAET TRAINING
COLLEGE , NETTAYAM

2. Name of the teacher : Renjini R
Name of the school : Govt.G.H.S.S.Cotton Hill
Standard : IX
Subject : Physics
Unit : Motion
Topic : Newton's third law of motion,
Conservation of momentum
Date : 14/07/14
Duration : 45 min
Strength : 40
Period : 3

3. Curricular Statement
Through observation and
communication, the pupils understand
about the nature of Newton's third law of
motion, conservation of momentum

4. Terms
Newton's third law of motion,
conservation of momentum
Facts
 Gun recoils after firing a shot.
 A boat goes backwards when a person
jumps from it.
 Momentum is the product of mass and
velocity of the body.

5. Concepts
To every action, there will be an equal and opposite
reaction.
Law of conservation of momentum:-If an external
force is absent, then the total momentum of a system
will always be constant

6. Learning Outcome
1.Storage
The pupil views power point presentation related
to motion.
2.Explore
The pupil search more details related to the topic
Newton’s third law of motion.
3.Application
The pupil prepares text material related to the
topic Newton’s third law of motion.

7. Previous Knowledge
i) The pupil knows about Newton’s first
law of motion and Newton’s second law
of motion.
ii)The pupil knows about momentum
Teaching Learning Resources
•Laptop
•Chalkboard

8. Preparation
Today we are going to study in a
different manner. I will show you some
pictures in the following slides. You
should carefully observe it. Then we
will have discussion on it.

9. Presentation
Activity-1
The following slide has a picture
sequence in which an experiment is
shown. Observe it and then write
answers for the given discussion
points.

10. Assume that the empty tea
bag is a rocket

11. Discussion points
• What do you observe in the above picture?
• If you assume the empty teabag as a rocket,
what happened to it when it is lighted?
• Why did the tea bag moved upwards?
• What is the action here?
• What is the reaction?

12. Concept to be consolidated
Ignition of empty tea-bag
(rocket) is action and upward
movement of tea- bag (rocket)
is reaction

13. Activity-2
Now look at the following slide
having the examples for Newton’s
third law of motion.

14. Newton’s Third Law of Motion

15. Discussion points
What are the instances you observed in the above
slide?
A person jumps to the shore from a boat floating on
water.
• What happens to the boat when the person jumps?
• Which is the action and reaction in the situation?
• Is the action and reaction takes place in the same
body?
• Are the action and reaction equal/unequal?
• Are action and reaction takes place in the same
direction?

16. Concept to be consolidated
 Newton’s third law of motion states
that “To every action, there will be an
equal and opposite reaction.
Action and reaction are equal in
magnitude but opposite in direction

17. Activity-3
Now look at the following slide
having a picture sequence which
shows the experiment on
conservation of momentum using
bobs.

18. Conservation of Momentum

19. Discussion points
i. What happens when one ball is moved away and
made to strike on other balls?
ii. What happens when two balls are moved away
and made to strike on other balls?
iii. What happens when the same experiment is
repeated using three balls?
iv. If the ball has mass ‘m’ and velocity ‘v’ , then
what will be the momentum for three balls?
v. Can you state the relation of momentum of
three balls before collision and the other three
balls after collision?

20. Concept to be consolidated
Total initial momentum of a system
before collision will be equal to the total
final momentum of the system after
collision. There is no change in the
momentum of the system.

21. Activity -4
PROBLEM
If a shot of mass 0.05kg is fired from a gun
of mass 20kg, Velocity of the shot is 200
m/s and backward velocity of gun is
0.5m/s. Find out the total momentum
before and after firing :-

22. Discussion points
• What is the expression to find out
momentum?
• What is the momentum of the shot?
• What is the momentum of the gun?
• What is the total momentum?
• Is momentum conserved here?
• How did you understand the conservation of
momentum?

23. Concept to be consolidated
In the absence of an external force,
the total momentum of a system
will always be a constant. This is
the law of conservation of
momentum.

24. REVIEW
• State Newton’s third law of
motion :-
• State law of conservation of
momentum:-

25. APPLICATION
A shot of mass 20g is fired from a
gun of mass 2 kg with a velocity
50m/s. Then what will be the
backward velocity of the gun?

26. Follow up activity
Find out four examples for
Newton’s third law of motion
from our day to day life. Write
down the action and reaction in
them:-