NEET-XII-Physics
10: Rotational Mechanics
- #4If there is no external force acting on a nonrigid body, which of the following quantities must remain constant?
(a) angular momentum
(b) linear momentum
(c) kinetic energy
(d) moment of inertia.digAnsr: a,bAns : (a) angular momentum
(b) linear momentum
`` {\stackrel{\to }{F}}_{ext}=0``
`` \Rightarrow {\stackrel{\to }{\tau }}_{ext}=0``
`` ``
That is, the change in linear momentum and angular momentum is zero. This is because:
`` \frac{\mathit{d}\stackrel{\mathit{\to }}{P}}{\mathit{d}t}\mathit{=}{\stackrel{\mathit{\to }}{F}}_{\,\mathrm{\,ext\,}}``
`` \,\mathrm{\,And\,}\frac{\mathit{d}\stackrel{\mathit{\to }}{L}}{\mathit{d}t}={\stackrel{\to }{\tau }}_{\,\mathrm{\,ext\,}}``
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