Question

If there is no external force acting on a non-rigid body, which of the following quantities must remain constant?

• A. Angular momentum and linear momentum.
• B. Torque.
• C. Kinetic energy and potential energy.
• D. Moment of inertia.

Answer 1

Answer: (A), (C), (D)

The correct options are
A Angular momentum and linear momentum.
C Kinetic energy and potential energy.
D Moment of inertia.

$\begin{array}{c}\text{Given-* No external foru acting on a non-rigid}\\ \text{body.}\\ \text{- Sinu the body is non-rigid and hence can change}\\ \text{its moment of Inertia by some Internal forces.}\\ \text{- Sinu no external foru is acting on the body}\\ \text{and therefore no torque will be applied onto}\\ \text{the Body.}\end{array}$

$\begin{array}{c}\text{- If no torque is applied on the body henu the}\\ \text{angular momentum of the body and linear}\\ \text{momentum will remain conserved.}\\ \text{- No external foru is applied on the body therefore}\\ \text{the Kinetic energy and Potential energy of the}\\ \text{Body remains constant.}\\ \text{Hence, option (A), (C), (D) are correct.}\end{array}$