Circular Motion

Demo 1: Newtonian Mountain

Newton's Cannon on a Mountain

What force causes circular motion?

What happens if you shoot it too fast?

What is the direction of the velocity at each point?

Demo 2: Object on Turntable

What force causes circular motion?

What happens when it goes too fast?

Demo 3: Spinning Object on StringWhat force causes circular motion?

What happens when you let go of the string?

A car moves around a circular track at 40 mph. Are the speed and velocity of the car constant?

Speed is constantVelocity is not constant because direction is changing. If the velocity is changing then the car is accelerating.

centripetal

Latin, “center seeking”

Centripetal Acceleration (ac)

The acceleration of a rotating or revolving object that is directed toward the center of its circular path.

ac = v2 tangential velocity

r radius

Centripetal force (FC)A force that causes an

object to take a circular path

Directed toward the center of the circular path

NOT a new force, old forces such as Fg, Ff, FN, Fa, tension, etc. act as a centripetal force

Fnet = m a

Fc = m ac

Fc = m v2

r