1. Force and Motion Motion Force Friction
A change in the position of an object when compared to a reference point
A reference point is any stationary object
Any push or pull
All motion is caused by a force
A force that opposes motion whenever two objects are touching

2. The force that pulls all objects toward the center of the Earth
Gravity
Summary
The force that pulls all objects toward the center of the Earth
Gravity is a force that opposes motion
There are four forces: push, pull, friction and gravity
Push or pull cause all motion
Friction and gravity try to stop all motion

3. Isaac Newton, 1687 Founder of Physics
A science that explains how things move
His research led to the Laws of Motion
He created an entire branch of math to prove his scientific laws

4. A stationary object needs a force to start its motion
First Law of Motion
Inertia
Every object remains at rest or moves with a constant speed in a straight line unless acted upon by a force
A stationary object needs a force to start its motion
An object at rest wants to stay at rest
A moving object will continue to move until a force stops it
An object in motion wants to stay in motion
The resistance of any mass to any change in its motion
Same as First Law of Motion