Question

A flywheel has a mass of 25kg has a radius of 0.2m. What force should be applied tangentially to the rim of the flywheel so that it acquires an angular acceleration of 2rad/s^2?

(a) 2N

(b) 5N

(c) 3N

(d) 1N

Answer 1

Correct answer is (b) 5N

To explain: M = 25kg, R = 0.2m, α = 2rad/s^2

Moment of inertia of the flywheel about its axis,

I = 1/2 MR^2=1/2×25×0.2^2=0.5kgm^2

As torque, τ = F×R=I×α

Therefore, Force F = Iα/R=(0.5×2)/0.2=5N.