How Is Rotational Kinetic Energy Calculated for a Cylinder Rolling Down a Ramp?

[map7s]

A 2.4 kg cylinder (radius = 0.09 m, length = 0.50 m) is released from rest at the top of a ramp and allowed to roll without slipping. The ramp is 0.74 m high and 5.0 m long. What is its rotational kinetic energy?

I just wanted to make sure that I was on the right track...

I=2/5 mr^2
KE=1/2 mv^2 + 1/5 mv^2

Using conservation of energy: mgh=1/2 mv^2 + 1/5 mv^2 and then solve for v and plug into equation for KE.

Does this sound like I'm doing this correctly?

 

[Doc Al]

I just wanted to make sure that I was on the right track...

I=2/5 mr^2
KE=1/2 mv^2 + 1/5 mv^2

You are on the right track, but you are using the wrong formula for rotational inertia. (2/5 mr^2 is for a rolling ball, not a cylinder.)