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When there are forces acting on a rigid body, the two conditions that has to be satisfied for the body to be in static equilibrium are:
1. The sum of all forces must be zero (translational equilibirum): $$\sum_i F_i = 0$$
2.The sum of all torques relative to any point must be zero (rotational equilibrium): $$\sum_i \tau_i=0$$
Why does the torque have to be zero relative to any point? My understanding is that as long as torque is zero with respect to the pivot, the body will not be in rotational motion. What does it mean when you talk about torque with no reference to a pivot?
Also, how can you makes sure that torque is zero relative to any point? Do you consider all the possible points?