Total kinetic energy for rolling hoop

[vetgirl1990]

Homework Statement

A hoop has a mass of 200g and a radius of 25cm (I_CM = MR² ). It rolls without sliding along level ground at VCM = 5m/s. What is it's total kinetic energy?

Homework Equations

K = 1/2Iω²
I_CM = MR²
v = rω

The Attempt at a Solution

The answer is 5J, but I'm getting 2.5J.

I_CM = MR² = (0.2)(0.25)(0.25) 0.0125
ω = v / r = 5/0.25 = 20

K = 1/2(0.0125)(20)² = 2.5J

Am I omitting something from the total kinetic energy equation?

 

[azizlwl]

You should consider translational motion too.

 

[vetgirl1990]

You should consider translational motion too.

Thanks! I forgot that a rolling object experiences both translational AND rotational motion. D'oh!