Rotational kinetic energy question

Question

A typical ten-pound car wheel has a moment of inertia of about .35 kg m^2 . The wheel rotates about the axle at a constant angular speed making 50.0 full revolutions in a time interval of 5.00 seconds.

What is the rotational kinetic energy K of the rotating wheel? In joules

Answer 1

Rotational KE = 0.5 * I ω^2

ω = 50 / 5 * 2π

ω = 20π rad / s

KE = 0.5 * 0.35 * (20pi)^2

KE = 691 J

BRUZER, I did, I really did, bugger. Edited it in now, but points to you for sure.

Answer 2

ke (rot) = .5 I w^2

I=.35kgm^2

w=50/5rev/s*2 PI rad/rev=62.8 rad/s

w^2=3947.8(rad/s)^2

ke=.5*(.35kg m^.2)*3947.8 (rads/s)^2=690.9kg m^2/s^2=690.9J

Looks like the first guy forgot to square the omega.