# Kinetic energy in rotating objects.

1. Oct 13, 2008

### Duely Cack

1. A 75-g phonograph album of 30-cm diameter spins at 33.3 rpm. What is its kinetic energy?

2. 1/2mv2

3. well i think that kinetic energy is 1/2mv2 so is it like that but instead of v you put in the 33.3 rpm. like 1/2(75)(33.3)2 maybe?

2. Oct 13, 2008

### Rake-MC

$$K_e = \frac{1}{2}I\omega^2$$

You have to use omega as radians per second, mass has to be in kilograms.