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Physics - Rotation Question with Solution | TestHub

PhysicsRotationMiscellaneousEasy2 minPYQ_2020

PhysicsEasysingle choice

A circular disc $A$ of radius $r$ is made from an iron plate of thickness $t$ and another circular disc $B$ of radius $4 r$ is made from an iron plate of thickness $\frac{t}{4}$ . The relation between the moments of inertia $I_{A}$ and $I_{B}$ is

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Answer:

Solution:

Disc	$A$	$B$
Radius	$r$	$4 r$
Thickness	$t$	$\frac{t}{4}$

$\frac{I_{A}}{I_{B}} = \frac{\frac{1}{2} m_{A} r_{A}^{2}}{\frac{1}{2} m_{B} r_{B}^{2}} = \frac{m_{A} r_{A}^{2}}{m_{B} r_{B}^{2}}$

$\frac{I_{A}}{I_{B}} = \frac{{πr}_{A}^{2} t_{A} r_{A}^{2}}{{πr}_{B}^{2} t_{B} r_{B}^{2}}$

$\frac{I_{A}}{I_{B}} = \frac{r_{A}^{4} t_{A}}{r_{B}^{4} t_{B}} = {(\frac{1}{4})}^{4} (\frac{4}{1})$

$\frac{I_{A}}{I_{B}} = \frac{1}{64}$

$∴ I_{A} < I_{B}$

Stream:NTA_ABHYAS_NEETSubject:PhysicsTopic:RotationSubtopic:Miscellaneous

⏱ 2mℹ️ Source: PYQ_2020

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