# Rotational Speed of a Uniform Disk

A uniform disk with a mass of 895 g and radius 17.0 cm is rotating on frictionless bearings with a rotational speed of 18.0 Hz when Jill drops a 120 g clod of clay on a point 7.90 cm from the center of the disk, where it sticks. What is the new rotational speed of the disk?

I was given the equation w=2(pi)F?

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#### Solution Preview

Hello there and thank you for posting your question to Brainmass.

The idea here is to use the principle of conservation of angular momentum.

Whet we have her is inelastic collision.

Initially the angular momentum (Ji) is just that of the disk.

It is given by:

Ji = Id * wi

where wi is the initial angular speed of the disk and (Id) is the moment of inertia of the disk.

After the particle sticks to the disk, the total final angular momentum (Jf) is the sum of the angular momentum of the disk and ...

#### Solution Summary

330 words of explained calculations show how to use angular momentum to calculate the rotational speed of a disk.