# Rotational velocity

1. Jun 26, 2003

### einsteinian77

How could i calculate the velocity of an object rotated around a fixed point such as a hand on a clock. It seems as though each section of the hand would have a different velocity, the end part being the fastest while the beginning part being the slowest if not moving at all. Im guessing the velocity would be expressed in frequency somehow.

2. Jun 26, 2003

### arcnets

That's correct, einsteinian77. Since the rotational velocity v increases proportional with radius r (distance from center), you define the angular velocity
[nu] = v/r.
This is the same for all points. The unit is 1/s. You could also say it's radians per second, since by integrating you get the angle:
[alpha] = a/r
where a is the arc length, and [alpha] is measured in radians.

Last edited: Jun 26, 2003