6. A wheel six meters in a diameter?

A wheel six meters in a diameter rotates on a fixed frictionless horizontal axis about which the rotational inertia I is 20 kg. a constant tension of 60 n is maintained on a rope of wrapped around the rim of the wheel. If the wheel starts from rest at t=0s find the length of the rope at t=0 seconds and find the length of the rope unwound at t=4s