Physics Rotational Kinematics HELP!!?

Question

Hello! I have 3 questions:

A 15 kg uniform disk of radius R = 0.25 m has a string wrapped around it, and a m = 4.6 kg weight is hanging on the string. The system of the weight and disk is released from rest.
a) When the 4.6 kg weight is moving with a speed of 1.3 m/s, what is the kinetic energy of the entire system?
b) If the system started from rest, how far has the weight fallen?
c) What is the angular acceleration at this point?

I don't know how to start. Any help/ideas? Thanks :)

Answer 1

See ref. below

a ) I = 0.5 m R^2

Ke (total) = Ke(weight) + Ke (disk)
Ke(weight)=0.5mV^2
Ke (disk)=0.5 I w^2
w= V/R

b) Ke=Pe=mgh
h=Ke/mg=0.5 V^2 / g

c) see ref again