PURPOSE: To demonstrate that equilibrium of forces is an insufficient condition for static equilibrium.

DESCRIPTION: The weight of the rod is balanced, with the rod held in a horizontal position, using two equal weights hung over pulleys. While holding the rod fixed, move a small weight from one side to the other. The force condition for equilibrium is still met, but the torque condition is not the same, and the rod will rotate.

SUGGESTIONS:

REFERENCES: (PIRA 1J40.40)

EQUIPMENT: Pre-assembled as photographed.

SETUP TIME: None.