Quote:
Originally Posted by 8cd03gro
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. . .
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There can be an equal and opposite force that makes the net force equal to 0, thus preventing any acceleration. But that doesn't mean each force no longer exists. They simply exist in balance. It only ceases to exist theoretically after doing the vector addition. But both the applied force, and the reaction force are still there.
As a practical example, if you hold a weight out at arms length you feel gravity pulling it down. Consider that the applied force to your arm. To hold it still, you must exert a force to counter gravity, a reaction force. With what you seem to be proposing is that since the thing you're holding is not moving, it must therefore be weightless, which is absurd and untrue. Force exists without movement, and continues to exist despite equal opposition.