# A solid ball - kinetic energy and angular speed

1. Feb 24, 2004

### HandcuffedKitty

A solid ball of mass 1.30 kg and diameter 19.0 cm is rotating about its diameter at 65.0 rev/min.

What is its kinetic energy?????

Also, if an additional 2.60 J of energy are supplied to the rotational energy,

what is the new angular speed of the ball?????

2. Feb 24, 2004

### Integral

Staff Emeritus
Rotational kintic energy is given by

$${KE = \frac 1 2 I \omega^2$$

Where I is the moment of initera and $$\omega$$= angular velocity.

3. Feb 24, 2004

### HandcuffedKitty

Thanks alot

That doesn't help any

4. Feb 24, 2004

### Loren Booda

Were you given that, for a solid sphere, I=2MR2/5 ?

How many radians are there in a revolution?