A flywheel of moment of inertia $0.4 K g / m^{2}$ and radius $0.2 m$ is free to rotate about a central axis. If a string is wrapped around it and it is pulled with a force of $10 N$ then its angular velocity after $4 s$ will be

5 r a d / s

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20 r a d / s

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10 r a d / s

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0.8 r a d / s

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Solution

The correct option is C $20 r a d / s$
The string provides a torque on the flywheel. We have torque as $τ = I α$ .
Thus
$F r = I α$
or
$10 \times 0.2 = 0.4 \times α$
or
$α = 5 r a d / s^{2}$
Thus after 4 seconds we have the angular velocity as
$ω = 0 + 5 \times 4$
$= 20 r a d / s$

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A flywheel of moment of inertia 0.4Kg/m2 and radius 0.2m is free to rotate about a central axis. If a string is wrapped around it and it is pulled with a force of 10N then its angular velocity after 4s will be

The correct option is C 20rad/sThe string provides a torque on the flywheel. We have torque as τ=Iα. ThusFr=Iαor10×0.2=0.4×αorα=5rad/s2Thus after 4 seconds we have the angular velocity asω=0+5×4=20rad/s

A flywheel of moment of inertia $0.4 K g / m^{2}$ and radius $0.2 m$ is free to rotate about a central axis. If a string is wrapped around it and it is pulled with a force of $10 N$ then its angular velocity after $4 s$ will be

The correct option is C $20 r a d / s$
The string provides a torque on the flywheel. We have torque as $τ = I α$ .
Thus
$F r = I α$
or
$10 \times 0.2 = 0.4 \times α$
or
$α = 5 r a d / s^{2}$
Thus after 4 seconds we have the angular velocity as
$ω = 0 + 5 \times 4$
$= 20 r a d / s$