1. Section 4-4

2. Tendency of an object to stay at rest or in motion. Because of inertia, an object at rest tends to stay at rest and an object in motion tends to keep moving at a constant speed in a straight line.

3. Newton’s first law states that an object will remain at rest or move at a constant speed in a straight line unless it is acted on by an unbalanced force.

4.  What happens when you are riding in a car and the car comes to a sudden stop?  What happens when the car starts going again?  In baseball, inertia tends to keep a player running in a straight line, as a result, base runners “round” the bases instead of making sharp turns.