Fred's life is too complicated. "I can't keep up with it all!" he cries. "I must slow things down ... I know -- I'll stop the Earth from rotating!"

Fred
grabs a giant steel girder,
hops into space,
and jams the girder hard against the surface of the Earth
at the equator.
The incredible grinding, scraping friction provides
a steady friction force of
**F = 1 billion Newtons**
against the ground.

- What is the moment of inertia of the Earth?
- What is the initial angular velocity of the Earth?
**(a vector)** - What is the friction force Fred is applying to the Earth?
**(a vector)** - What is the torque Fred is applying to the Earth?
**(a vector)** - What is the angular acceleration of the Earth?
**(a vector)** - Assuming that Fred can maintain this same force for a long time, how long will it take him to halt the Earth's rotation?
- How long has the Earth been in existence?
- How long will the Sun continue to shine?

*(if you have time)*

Copyright © Michael Richmond. This work is licensed under a Creative Commons License.