Weight on a pulley, torque, mechanical energy

[maxbashi]

Homework Statement

A block of mass (m1) is attached by a massless string to a pulley of mass (m2) with radius R. Starting from rest, what is the block's speed after it has fallen height h?

Homework Equations

I'll call angular velocity w.
I'm thinking conservation of mechanical energy, so (m1)gh = (1/2)(m1)v^2 + (1/2)Iw^2
Moment of inertia for the pulley would be (1/2)(m2)r^2

The Attempt at a Solution

(m1)gh = (1/2)(m1)v^2 + (1/2)[(1/2)(m2)r^2](v^2/r^2)
simplifying would give
v=sqrt[(m1gh) / (.5(m1) + .25(m2))]

Is this right?

 

[ehild]

Yes.

ehild