PURPOSE: To show that pendula of different length suspended from the same point rotating at the same angular speed rise to the same vertical height.

DESCRIPTION: When the device is rotated at an angular speed w the angle a from the vertical which a pendulum of length l will assume is given by cos a = g / w^2 l, where g is the acceleration of gravity. The vertical distance of each from the support point is l cos a = g / w^2, the same value for each of the pendulum. This can be easily observed using the apparatus.

SUGGESTIONS: Accelerate slowly, then maintain constant angular speed.

REFERENCES: (PIRA unavailable.) This is a sample problem, Halliday and Resnick, Fundamentals of Physics, Vol. 1, third edition, pages 112-113.

EQUIPMENT: Base from rotating stool, rod, three golf balls on strings, and guide wires.

SETUP TIME: 10 min.

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