Rotational MotionHard

Question

A string is wrapped around the rim of a wheel of moment of inertia 0.20 kg-m2 and radius 20 cm. The wheel is free to rotate about its axis and initially the wheel is rest. The string is now pulled by a force of 20N. The angular velocity of the string after 5 seconds will be : -
                                                 

Options

A.90 rad/s
B.70 rad/s
C.95 rad/s
D.100 rad/s

Solution

For angular acceleration τ = Iα
Φ 20 × 0.2 = 0.2 × α ⇒ α = 20 rad/sec2
∴ ω = ω0 + αt =  + 20 × 5 = 100 rad/sec

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