A flywheel of moment of inertia `0.4 kg-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 10N, then its angular velocity after `4s` will be
Options:
(a) `10 rads^(-1)`
(b) `5 rads^(-1)`
(c) `20 rads^(-1)`
(d) None of these