System Of Particles And Rotational Motion Ques 45

45. A disc is rotating with angular velocity $\omega$. If a child sits on it, what is conserved ?

[2002]

(a) Linear momentum

(b) Angular momentum

(c) Kinetic energy

(d) Moment of inertia

Show Answer

Answer:

Correct Answer: 45.(b)

Solution:

  1. (b) If external torque is zero, angular momentum remains conserved.

$L=I \omega=$ constant

External torque is zero because the weight of child acts downward