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Question
If the resultant torque of all the forces acting on a body is zero about a point, is it necessary that it will be zero about any other point?
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Solution
No, it is not necessary that the torque about any other point be zero if it is zero about one point.
Let \[\overrightarrow{F}\] be the resultant force due to all the forces acting on the plane of the body. Therefore, torque due to force \vec{F} at any point will be the resultant torque . Now, we see that the torque due to \[\overrightarrow{F}\] at point Q will be zero because Q lies on the line of support of the force F but the torque due to force \[\overrightarrow{F}\] will not be zero along the point P.
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