1. Newton’s 3rd Law Notes and Examples
Chapter 10

2. Newton’s 3rd Law
Newton’s 3rd Law states:
For every action force, there is an equal and opposite reaction force.
If they are equal and opposite, why don’t they cancel out?
Since the forces act on different objects, they do not cancel.
The objects have different amounts of inertia, and therefore react to the force differently

3. Ex: girl passing volleyball
The action force is: the girl pushing the volleyball
The reaction force is: the ball pushing on her wrists with equal and opposite force
The action force is being placed on the ball, while the reaction force is being placed on the wrists.
Notice the arrows are equal in length = equal magnitude (force strength)

4. Turn over your paper As a table group on your white board:
Identify the action force
Identify the reaction force
Illustrate your example
Use labeled arrows to show the action and reaction forces

5. Leaning against a wall Action force: pushing against the wall
Reaction force: wall pushing back. A R

6. Hammering a Nail Action: hammer pushing the nail
Reaction: nail pushing the hammer back
Equal and opposite, but movement is not.
Why?
Hammer has more inertia! (More mass = more inertia = more force to move it)

7. Rocket Lifting off Action: rocket fuel pushing on ground
Reaction: ground/air, pushing on rocket fuel

8. Walking Action force: feet pushing on the ground
Reaction: ground pushing back

9. Penguin swimming through ocean
Action: penguin pushing the water
Reaction: water pushing back on penguin
Reaction
Action

10. Baseball bat hitting a baseball
Action: bat pushing on ball
Reaction: ball pushing on bat
Why does ball move further than bat?
Ball = little inertia
Bat + you = lots of inertia
Reaction
Action

11. Kicking a Soccer ball Action: foot pushing ball
Reaction: ball pushing back on foot
Forces are equal, and opposite, but movement is not.
Why? Ball = little inertia
Foot/body = lots of inertia. R A

12. Skydiver falling through the air
Action: person pushing on air
Reaction: air resistance pushing back A R

13. Bowling ball hitting pins
Action: ball pushing pins
Reaction: pins pushing back A R