A flywheel of the moment of inertia 0.4 kg m2 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

Question

A flywheel of the moment of inertia 0.4 kg m2 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 (A) 10 rad s- 1 (B) 5 rad s- 1 (C) 20 rad s- 1 (D) None of these

Tardigrade Admin · Accepted Answer

F × r=I α=I ((ω2-ω1)/t) ∴ ω 2-ω 1=(F × r × t/I) =(10 × 0.2 × 4/0.4)=20 rad s- 1

Q. A flywheel of the 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

$10 r a d s^{- 1}$

$5 r a d s^{- 1}$

$20 r a d s^{- 1}$

None of these

$F \times r = I α = I \frac{( ω _{2} - ω _{1} )}{t}$
$∴ ω_{2} - ω_{1} = \frac{F \times r \times t}{I}$
$= \frac{10 \times 0.2 \times 4}{0.4} = 20 r a d s^{- 1}$

Q. A flywheel of the moment of inertia 0.4kgm2 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

10rads−1

5rads−1

20rads−1