Rotational Equilibrium

Purpose:

To show that the sum of the torques is zero when a body is in rotational equilibrium.

Equipment:

Irregular plate, supports and pulleys, set of weights, string, one support with rod to fit loosely into center hole in plate, plumb bob, large protractor, meter stick.

Procedure:

1. Mount plate by inserting support rod. Tie strings to holes on rim of plate. Position strings over pulleys and hang weights on ends. Calculate torques and verify that in equilibrium the sum of the torques is zero.
2. Measure angles of forces using plumb bob as a vertical reference. By setting sum of horizontal and vertical components equal to zero, show that force exerted by axis is zero. Remove axis.