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6. system of particles and rotational motion — Physics STD 11 Science — Question

Gujarat BoardEnglish MediumSTD 11 SciencePhysics6. system of particles and rotational motion1 Mark
MCQ
A disc of mass  $M$  and radius  $R$  is rolling with angular speed $\omega $ on a horizontal plane as shown. The magnitude of angular momentum of the disc about the origin $O$ is
  • A
    $\frac {1}{2} MR^2\omega $
  • B
    $MR^2\omega $
  • ✓
    $\frac {3}{2} MR^2\omega $
  • D
    $2MR^2\omega $
✓

Answer

Correct option: C.
$\frac {3}{2} MR^2\omega $
c
Angular momentum of disc about origin is $:$

$\mathrm{L}=\mathrm{I} \omega+\mathrm{mV}\left(\mathrm{r}_{1}\right)$

$=\frac{\mathrm{MR}^{2}}{2} \omega+\mathrm{mV}(\mathrm{R})$

$=\frac{\mathrm{MR}^{2}}{2} \omega+\mathrm{M}(\omega \mathrm{R})(\mathrm{R})$

$=\frac{3}{2} \mathrm{M} \omega \mathrm{R}^{2}$

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