1. The problem statement, all variables and given/known data When a body is weighed on an ordinary balance we demand that arm should be horizontal if the weights on two pans are equal. Suppose equal weights are put on two pans, the arm is kept at an angle with the horizontal and released. Is the torque of the two weights about the middle point (point of support) zero? Is the total torque zero? If so, why does the arm rotate and become horizontal? 2. Relevant equations 3. The attempt at a solution Here's what i think so far:- (Sorry for a bad drawing :) ) For the first part, individual torque is not zero. For each weight the torque is mgrcosθ. For the second part, the total torque is zero since the torques of weight are in opposite direction. Now i am confused in third part. Since the net torque is zero, the balance should not move but thats not observed. Then why does it come to the horizontal position?