Chapter 3: Describing Motion

Velocity

• Track stars are always asked the same questions:

• What distance do you run.

• And what was your time.

Measuring Distance

So If We Have a Reference Point

Finding the Average Velocity

Calculating Acceleration

Review of Dimensional Analysis

Velocity Continued

Position Versus Time

Force and Motion

• A force is a push or pull one body exerts on another

• Forces balance if the forces are equal in size and opposite in direction

Inertia

• An object will tend to do whatever it is doing unless a force is applied to it.

– If it is resting it will tend to stay resting

– If it is moving it will keep moving with the same speed and same direction

(Newton’s First Law)

• Why do we not see this happening all the time in the “real world”?

Friction and Gravity

• Friction is caused when 2 objects are moving and are touching each other

• Gravity is the force that every object in the universe feels and causes (depending in the mass of the object and the distance between)