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

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

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

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