Randomly fluctuating torque

Here I = 7.5 X 1015 g-cm2/mol is the moment of inertia of the ring about the torsional axis, 7/3 is the friction constant, k is the harmonic restoring force constant, and/(f) represents the random torques acting on the ring due to fluctuations in its environment. In using the Langevin equation, we implicitly assume that variations in/(f) occur on a much shorter time scale than do... 

An agitator shaft is loaded by torque, supplied by the motor, which is a relatively steady force, with no more than 5-10% variation during normal operation, and bending caused by uneven loading of agitator blades, which is random and continuously fluctuating. 

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