Question

When slightly different weights are placed on the two pans of a beam balance, the beam comes to rest at an angle with the horizontal. The beam is supported at a single point P by a pivot. Then which of the following statement(s) is/are true ?

• A. The net torque about P due to the two weights is nonzero at the equilibrium position.
• B. The whole system does not continue to rotate about P because it has a large moment of inertia.
• C. The centre of mass of the system lies below P.
• D. The centre of mass of the system lies above P.

Answer 1

The correct option is A The net torque about P due to the two weights is nonzero at the equilibrium position.

The whole system does not continue to rotate about P because the moment is balanced. Thus option B is wrong. And the center of mass of the system lies at pivot point P. Thus option C and D are wrong. As the force applied at the two points of suspension is different $\tau$ is different.