KE of Rotation & Moment of Inertia

[valeriex0x]

Homework Statement

A light string is wrapped around the outer rim of a solid uniform cylinder of diameter 75.0 cm that can rotate without friction about an axle through its center. A 3.00 kg stone is tied to the free end of the string, as shown in the figure . When the system is released from rest, you determine that the stone reaches a speed of 3.50 m/s after having fallen 2.50 m.

What is the mass of the cylinder?

Homework Equations

KE=1/2(1/2MR^2)ω^2

v=rω

The Attempt at a Solution

v=rw
3.50=.375w
w=9.3

ke=1/2(1/2M(.375)^2)(9.3)^2

I am doing this right and
is 30406kg correct?

 

[I like Serena]

Hi again valeriex0x!

What did you do with the kinetic energy of the stone?

Btw, the mass you found looks a bit large doesn't it?

 

[valeriex0x]

i got it