Answer to Question #168382 in Physics for Andu

Question

The mass of the 3 hanging stones on the right arm of the scroll is m = 100 g. Determine the mass of the body A hanging on the left arm, knowing that the bodies are in equilibrium

Answer 1

If the bodies are in equilibrium and the scroll hangs attached to a string right in the middle, the mass of the body A must be equal to the total mass of the three stones, that is, 100 g.

This can be achieved from the torque equilibrium:

$$M_s·d-M_A·d=0,\\ M_A=M_s.$$