Question

A string is wrapped around the rim of a flywheel 0.400 m in radius, and a steady pull of 50.0 N is exerted on the cord. The wheel is mounted in frictionless bearings on a horizontal shaft through it's center. The moment of inertia of the wheel is 4.00 kg.m^2 .Calculate the angular acceleration of the wheel.

Answer 1

Read up examples in
http://spiff.rit.edu/classes/phys211/lectures/rotke/rotke_all.html
one of which is similar to this one.

After this, you can attempt the previous problem you posted, together with your previous knowledge of kinematics and energy principles.

Answer 2

The torque T = 50N*0.4m
= 20N.m
The moment of inertia is I = 4.00kg.m^2.
The angular acceleration in rad/s^2 alpha = T/I
=20N.m/(4.00kg/m^2)
=5 rad/s^2