Question

Assertion (A): When a gramophone record starts rotating in a satellite then satellite starts rotating in opposite direction.
Reason (R) : Angular momentum of system of satellite and gramophone record is constant as there is no external torque.

• A. Both A and R are true and R is correct explanation of A
• B. Both A and R are true and R is not correct explanation of A
• C. A is true and R is false
• D. A is false and R is true

Answer 1

The correct option is A Both A and R are true and R is correct explanation of A

Angular momentum will remain same because no external torque is responsible for the rotation of satellite.
$\therefore L_1=L_2$
$I_1{\omega }_1=I_2{\omega }_2$
$I_1=I_2$( as clear from the question)
$\therefore {\omega }_1={\omega }_2$ (moreover, direction will be opposite)