A spinning wheel has some very strange forces acting on it. Click to see a 100kb movie.

Can you hold a bicycle wheel upright with one finger?

You can, as long as the wheel is spinning.

After viewing the movie on the left can you explain why it is hard to fall off a bicycle if it is moving at high speeds.

A spinning wheel produces strange forces. Tilting a spinning wheel is difficult. A spinning wheel exerts forces that oppose any external forces that act to tilt it.
The forces generated by the spinning wheel as it is tilted spin the person around on a rotating chair.

A gyroscope is a device for keeping track of the orientation of a moving object. In essence, a mechanical gyroscope is a spinning wheel whose axle is free to take any orientation, as shown on the right. Although the orientation of the moving object the gyroscope is placed in does not remain fixed, the spinning wheel of the gyroscope remains fixed regardless of any motion of the it is subjected to. Thew heavier the spinning wheel and the faster its rotation the more accurate the gyroscope.


Demonstrate the stability of a rotating wheel with a toy gyroscope as shown in the video on the right, a bicycle wheel on a table, or by holding a spinning bicycle wheel on a spinning chair.



Gyroscopes have applications where magnetic compasses would not work, as in the Hubble telescope, or in ICBMs.

Planes use gyroscopes to indicate their relative position in the sky, as shown on the right.