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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?
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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