"Not everything that counts
can be counted, and not everything
that can be counted, counts."

- Einstein

I. Uniform Circular Motion

Why can it be said that the earth
has a nearly uniform circular motion
around the sun?

The earth moves in a plane around the sun.
Define the geometric shape called a plane.

The earth and a motorcycle need something
in order to turn. What is that?

Y2K Ducati Women's Motorcycle Team

 "What does this picture tell you about the speed of these motorcyclists?"

Nina Prinz and Letizia Marchetti
- Ducati Women's Motorcycle Racing Team

 "A large centripetal (center directed) force in needed to turn at high speeds."

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St. Mary's H.S. Physics

Skater

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Rutgers U.

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 In order for an object to move at constant speed in a circle, an outside force must constantly turn the object toward the center of circular path.

Circular Motion, Car on a Banked Track

by Dr. Michael R. Gallis mrg3@psu.edu

Penn State Schuylkill

Go Nittany Lions!!

Draw the centripetal force,
and tangential velocity

Draw the centripetal force,
and tangential velocity

Draw the centripetal force, and tangential velocity

 Where should you release the ball to hit the target?

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B

 At point P, the car hits an area of ice and loses all frictional force on its tires. Which path does the car follow on the ice?

June 2001 Regents

 B, Tangent to the semi-circle

 Circular Motion Equations