Suppose we have an ordinary balance where equal weights are put in both sides. Now one side is slowly held down. When this force is not applied anymore, the balance tends to achieve horizontal position.
But when one side is held down, the moment of force due to both weights are equal in magnitude and opposite in direction. Also, the potential energy of the system remains same (As the height lost by one weight is equal to the height gained by another). So why does the balance try to regain horizontal position?
Here $r$, $F (=mg)$ and $\sin \theta$ are equal
