Quote:
Originally Posted by DGthe3
The displacement vector is from the axis about which the force is being applied to the point which the force is being applied. Nothing requires that it actually rotates about the axis. Merely that it is drawn from that axis to the applied force. The forces can balance out, and nothing will move. But that does not mean there is no torque, just no movement.
In fact, 'static torque' is far more common in the world than 'dynamic torque' is. Usually, its refered to as a moment (particularly in structural engineering circles) but it is identical in concept to torque. Whether its a beam supporting a load, or a guy trying to get a stuck lug nut off a wheel. Nothing is moving, but there are certainly forces applied at a distance, about an axis.
You may be thinking of work or power. They require movement, but torque does not.
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You are misunderstanding my point. The displacement vector isn't my concern, the force vector is. If there is no movement, any force vector must be cancelled out by another of equal magnitude in the opposite direction. If that's the case than the value of the total force vector is zero and if torque is the product of the force vector and displacement vector, then torque must be equal to zero. Maybe I'm just getting too caught up on the technicalities of the terminology. . .