PURPOSE: To measure the angular velocity of a rotating object.

DESCRIPTION: Various masses M can be hung on a string wound around an axle of either of two radii R to provide a torque T = MgR. Four brass masses m can be positioned along the arms at one of four distances l from the axis of rotation to provide a moment of inertia I = 4ml^2. The angular acceleration a = T/I = MgR/4ml^2 can then be calculated. The angular acceleration can be determined experimentally by measuring the time required for the system to rotate one complete revolution starting from rest: a = 2 d/t^2, where t is the time required for the device to rotate through the angle d in radians.

The angular velocity can be determined by simply measuring the time per revolution.

SUGGESTIONS:

REFERENCES: (PIRA 1Q20.20)

EQUIPMENT: Oberbeck cross with extender and manual timer.

SETUP TIME: None.