1. Newton’s Laws
Notes

2. Newton’s 1st law DO NOT WRITE THIS!!
You will hear the 1st law as the following:
“An object at rest will stay at rest, unless acted upon by an outside force”
“An object in motion will stay in motion, until it experiences and outside force”

3. Newton’s 1st law Why it’s Confusing:
Suggests there has to be an interaction with a force to change motion
However, forces are always acting on objects

4. Newton’s 1st law
2 PARTS
PART 1: Object at rest stay at rest (if forces are balanced)
Ex: weight lifter holding barbell, student sitting in chair, tug-o-war with equal teams.
PART 2: Object in motion stay in motion (if forces are balanced) Harder to believe
Ex: Car on cruise control, parachute at terminal velocity (Fair = Fg)

5. Newton’s 1st law You will also hear as….
LAW OF INERTIA (resisting change in motion)

6. Newton’s 1st Law SUMMARY:
The object will stay in the same state, unless there is a NET FORCE acting on it.
If there is a NET FORCE, then the object will change motion (positive or negative acceleration)

7. Newton’s 2nd law ACCELERATION DEPENDS ON FORCE and MASS
a = F/m OR F = m*a (more typical)
What would happen if the mass stayed the same, but we had less force?
(acceleration decrease)

8. Newton’s 3rd law
You will see written “For every action, there is an equal and opposite reaction”
DON’T WRITE THIS!!!
Why CONFUSING: sounds like a reaction happens AFTER the action, but we know they happen and interact at the same time

9. Newton’s 3rd law
When 2 objects interact, they both experience a force that is equal in size and opposite in direction
FORCES ACT IN PAIRS (better definition)