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From: Dave Steffen (dgsteffen_at_[hidden])
Date: 2006-08-23 14:47:31

Andy Little writes:
> The serious point was that there is a relation between torque and energy, but
> they are distinct.
> and actually the relation is slightly more complicated than I stated, but I
> think that for a bolt of N turns
> and assuming a constant torque, the heat dissipated (in Joules) ==
> applied_torque (in N.m) * N / (2 * pi).

 OK, hold on here.

 Work = change in energy = force * distance.

 (Actually, the integral of force * infinetesimal displacement, but
 let's assume constant forces here.)

 Torque = radius * Force. (Actually, it's a cross product, but let's
 assume the force is always perpendicular to the lever arm.)

 Therefore, for a given torque, Force = Torque / radius.

 So, the work done (delta engergy) in applying a constant torque to
 your bolt is

    W = Force * distance = ( Torque * distance ) / radius.

 Now, if you turn the bolt N times, the distance you've moved the end
 of your lever arm (where you're applying the force) is

   distance = 2 * pi * radius * N.
 Plugging this in,

   W = (Torque * 2 * pi * radius * N) / radius


 W = 2 * pi * N * Torque.

 [[ End of physics lesson ]]

Dave Steffen, Ph.D.
Software Engineer IV Disobey this command!
Numerica Corporation - Douglas Hofstadter
dgsteffen at numerica dot us

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