I with rotational kinetic energy problems

[kenny243]

I tried to use this formula: KE=(1/2)(I)(w)^2, and work=change in KEFor the first question, i tried to plug the number into the rotation kinetic energy formula:
3600rpm=376.8rad/s
(0.5)(2,000kg)(0.125m)^2(376.8rad/s)^2
I found out this was the answer 1.1 x 106 J, but I got 2218410J

For the second one, I did:
(0.5)(7kg)(0.109)^2((6m/s)/(0.1m))^2
And I got 21j, pretty sure is wrong.

Can someone please help me out, or give me a hint??
Really struggling.
Does the change in kinetic energy equal to work?

 

[haruspex]

I got 2218410J

I get about the same.

For the second one, I did:
(0.5)(7kg)(0.109)^2((6m/s)/(0.1m))^2

What's the formula for the MoI of a solid uniform sphere?