# Rotational Inertia in two cylinders

1. Mar 25, 2014

### TheAce3317

Calculate the kinetic energies of two uniform solid cylinders, each rotating about its central axis. They have the same mass, 1.25 kg, and rotate with the same angular velocity, 235 rad/s, but the first has a radius of 0.18 m and the second a radius of 0.73 m.

I got 12112188.868 for ω, and 0.050625 for I

I have been using I=mr^2, and .5*Iω^2

I plugged everything in with out changing any units, and got 1906125390.62499825 for the small one, which i know to be wrong. Then I thought I remembered something my teacher said about multiplying the radians by 2pi, and then I plugged all the numbers back in and got another large number.

2. Mar 25, 2014

### TheAce3317

nvm, ran out of time. getting help from my teacher tomorrow