The potential energy in problem 1 is given by U = mgy. That's 20 kg * 9.8 m/sec² * 200 m = 39,200 J.
I looked up the moment of inertia for a disk; it's I = 1/2MR². So for this disk, I = 1/2 * 20kg * (0.2m)² = 0.4kg*m²
To find the angular acceleration α, you need the angle θ of the slope of the incline. Then, you can find the maximum angular velocity. Convert this velocity to kinetic energy, and subtract it from the total potential energy. The remaining potential energy was converted to linear velocity, which you can find by converting the remaining potential energy back into velocity.
a) I = 140.625 Kg * m².
b) I sort of neglected torque when I took physics. Someone else will need to answer, or you can ask your teacher.
c) I neglected Power too
d) What is the diameter of the drum?