Third Law of Motion

1. NEWTON’S THIRD LAW-
Is it Rocket Science
Science 8 Teacher

2. Short Review

3. Question 1:
What is an Action?
Answer
• Something that is done.
• An act.

4. Question 2:
● What are some examples of Reactions?
Answer:
• When chemicals mix and a change occurs.
• When someone gets upset in response to what a
person says.
• When you throw a ball down onto the ground and it
bounces back.
• A response to something.

5. Question 3:
Write a statement that shows the difference
between an Action and a Reaction.
Answer:
● An action is the opposite of a reaction.
● A reaction is a response to an action.

6. Lesson Purpose and
Intention

7. Lesson Purpose and Intention
✔ To understand the
Newton’s 3rd Law of
Motion.

8. Lesson Language
Practice

9. Exert Action Reaction
Interation Thrust Recoil
Rocket
Practice Saying These Words

10. Lesson Activity

11. Lesson Activity

12. The following are all examples of everyday situations that
can be used to describe the Law of Action and Reaction:
1. The movement of a balloon when air is released from the neck of
the balloon.
2. The upward movement when a rocket ship takes off.
3. The way a slingshot works to project an object.
4. The recoil on a person’s shoulder when they fire a rifle.
5. The trail in the water from the propeller of a moving speedboat.
6. The recoil of a heavy cannon when it fires an iron cannon ball.
7. Pushing off the ground to walk or run.
8. Rowing a boat.
9. When a billiard ball hits another one, the second one moves with
the same force as the first, but the first stops or moves back.

13. Question 1:
The word ‘exert’ is used three times in the
information box provided. What is another
word that means the same as ‘exert’?
Answer:
Applies, or puts, or places, [not stop, or
travel]

14. Question 2:
Which of the 9 examples provided in the
information box involve gases exerting a force?
Answer:
Numbers 1, 2, 4, and 6.
1. The movement of a balloon when air is released from the neck of the
balloon.
2. The upward movement when a rocket ship takes off.
4. The recoil on a person’s shoulder when they fire a rifle.
6. The recoil of a heavy cannon when it fires an iron cannon ball.

15. Question 3:
What are the important differences between the
Scientific and Non-scientific meanings of ‘Action’ and
‘Reaction’?
Answer:
The scientific understanding about Action and
Reaction is that the two things ALWAYS happen at the
same time; Non-scientific ‘actions’ and ‘reactions’
don’t need to happen at the same time – there can
be a big time-gap between them.

17. Question 1:
What does gravity act on?
Answer:
• Anything that has mass. or Anything that
has weight.
• Common household objects around us, like
glasses and sports equipment.
• Not emotions or ideas.

18. Question 2:
What are some ways that humans use to overcome
or go against gravity?

19. Answer:
• We use ladders to climb off the ground.
• Elevators in tall buildings.
• Using trampolines or springboards helps
you go up against gravity.
• Using airplanes.
• Using rockets to get into space

20. Question 3:
Why do spaceships need huge rockets to get them
into space?

21. Answer:
• To escape the Earth’s gravity, a rocket needs to
exert a strong force down on Earth (the Thrust) to
propel the rocket upwards very fast. Escape velocity
is about 12 km/s, which is approximately 33 times the
speed of sound.
• As a rocket ship goes upwards through the
atmosphere, to reach escape velocity it needs to
carry all of its own fuel and oxygen and these are very
heavy, so the rocket is very big.

22. Lesson Conclusion

23. Question 1:
What did you learn from
this lesson?
Question 2:
What are some things
you enjoyed about the
lesson?

24. Question 3:
What are some things you
found difficult in this
lesson?
Question 4:
What is something you
would like to learn more
about in this topic?