Question

# A fly wheel of mass 140 kg and radius 3 m is rotating at 240 rpm. The angular acceleration of flywheel if it comes to rest, after 7 rotations is (Assume constant angular acceleration)

A
B
C
D

Solution

## The correct option is B −167π rads2Given, Initial angular velocity (ωo)=2π×24060=8π rads final Angular velocity (ωf)=0 rads Given that flywheel undergoes 7 rotations, so angular displacement θ=7(2π)=14π From Kinematics equation  ω2f−ω2o=2αθ 0−64π2=2α(14π) α=−16π7 rads2

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