System of Particles and Rotational Motion - Result Question 51
55. A solid sphere is rotating freely about its symmetry axis in free space. The radius of the sphere is increased keeping its mass same. Which of the following physical quantities would remain constant for the sphere? [2018]
(a) Angular velocity
(b) Moment of inertia
(c) Angular momentum
(d) Rotational kinetic energy
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Answer:
Correct Answer: 55. (c)
Solution:
- (c) Angular momentum, remains conserved until the torque acting on sphere remains zero. $\tau _{\text{ex }}=0$
So, $\frac{d L}{d t}=0$
i.e., angular momentum $L=$ constant.
