# How to find frequency of rotational motion without knowing radius?

##### 2 Answers

#### Explanation:

I assume that we are referring to a rigid object that rotates at a constant angular frequency

We know the linear speeds

For rigid rotation, it holds for any point on the solid that

Therefore we know that

which gives that

Now we can solve for

Using our newfound knowledge of the radius

Check that you get the same answer when using

Depends what you're asking.

#### Explanation:

It looks like there is a typo in your question. If what you are really saying is this: