1. Newton’s Third Law
Chapter 6

2. For every action there is an equal and opposite reaction. True or False?

3. What Actions?
Money?
Revenge?
Love?
Hitting?

4. For every FORCE there is an equal and opposite FORCE. Always True!

5. What Does it Mean?
Misconception: Actions are always equal and opposite.
I push you, you fall down.
Truth: Only forces are equal and opposite.
I push you, you push back on me.

6. What Does it Mean?
Misconception: Forces can be very large on weak materials like paper.
I can hit a piece of paper with a million Newtons of force.
Truth: You can only hit something as hard as it can hit you.
Paper is weak, so you can’t hit it very hard.

7. What Does it Mean?
Misconception: There are special cases where the law is not true.
If I sneak up on you, you won’t hit me back.
Truth: There are apparently no exceptions to the law.
You hit me back whether you mean to or not.

8. What Does it Mean?
Misconception: Since the forces are equal and opposite, they cancel each other out.
Truth: The forces ALWAYS act on different objects. Only forces that act on the same object can cancel out.

9. What Does it Mean?
Misconception: Because the forces are the same, the accelerations are the same.
Truth: Acceleration depends on force AND mass. The bigger mass will have less acceleration.

13. I hit the wall… What is the reaction force? Which force is bigger?
Which acceleration is bigger?

14. Bus hits car… What is the reaction force? Which force is bigger?
Which acceleration is bigger?

15. Horse and Cart
Newton’s Third Law

17. Explaining Freefall
Whenever mass gets bigger, the force of gravity gets bigger, too.
“g” is the ratio between force and mass.
“g” remains constant.

19. Force is the same for both objects!!

23. Sgt. Bilko