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Physics - Rotation Question with Solution | TestHub

PhysicsRotation283Medium2 minQB

PhysicsMediumsingle choice

As shown in the figure, a bob of mass $m$ is tied by a massless string whose other end portion is wound on a fly wheel (disc) of radius $r$ and mass $m$ . When released from rest the bob starts falling vertically. When it has covered a distance of $h$ , the angular speed of the wheel will be :

Options:

Answer:

Solution:

$m g h = \frac{1}{2} m v^{2} + \frac{1}{2} \times \frac{1}{2} m r^{2} \times \frac{v ^{2}}{r ^{2}} = \frac{3}{4} m v^{2}$

$v = \frac{4 g h}{3}$ , so $ω = \frac{v}{r} = \frac{1}{r} \frac{4 g h}{3}$

Answer (C)

Stream:JEESubject:PhysicsTopic:RotationSubtopic:283

⏱ 2mℹ️ Source: QB

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