How do I go about this?

Which equations should I be using?

Torque = Inertia x Angular acceleration

Angular Velocity = Angle/dt (Time I presume)

I have done

sa=((V+0)/2)40=20V

sb=((V+V)/2)60=60V

sc=((0+V)/2)20=10V

I could then do

W=dØ/dt

Then times by Inertia (400)

I get

a-200N

b-400N

c=200N

This seems too easy and whast the resisting torque value for? Do I just add this to part a, ignor for part b and take off for part c?

Tho I'd get a negitive vale for c then?

Cheers

Sheldon