PURPOSE: To illustrate the center of mass with a surprise.

DESCRIPTION: Insert the spoon between the tines of the fork and balance the system on the edge of the glass using a toothpick.

SUGGESTIONS: Burn the toothpick from the inside end, and ask the students when the system will fall. IT WON'T! The flame goes out when it gets to the edge of the glass and the heat is absorbed by the glass. The fork and spoon remain balanced..

Click here to see the toothpick set on fire using a match. Click on the photograph above to see whether the balance will fail when the flame reaches the support point of the toothpick.

See Question of the Week #106 for information on using this demonstration to enhance class involvement.

REFERENCES: (PIRA 1J20.20)

EQUIPMENT: Fork, spoon, toothpicks, glass, and matches, assembled as photographed.

SETUP TIME: None.