A rotary motion probe is used to first measure the angle at which a washer overcomes static friction so that the coefficient of static friction can be calculated from the μ=tanθ, relationship. The force of friction between the washer and a metal rod is then equated with the centrifugal force required to overcome the static friction between the washer and a rod undergoing angular acceleration. From this equality the theoretical velocity at which the washer begins to slide off of the rod is calculated. The theoretical velocity is then compared to the velocity for this occurrence as measured with rotary motion probe.

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