# Difference between rotational and angular velocity

1. Sep 26, 2003

### gio

Can anyone tell me the difference between "rotational velocity" and "angular velocity"?

I got that angular velocity is the dimension of angle/time, but rotational velocity is the dimension of rotations/time.

Will appreciate it if you can also provide me with some references defining the difference.

Last edited by a moderator: Sep 26, 2003
2. Sep 26, 2003

### HallsofIvy

Quite frankly, I don't recall seeing "rotational velocity".

I could see it as having either of two meanings:
number of revolutions per unit time- if angular velocity is w radians per second, then (since there are 2pi radians in a circle) the "rotational velocity" would be w/(2pi) revolutions per second.

The other possibility is the linear velocity of a point on the circumference of the circle. Since an angle theta in a circle of radius r subtends an arc of length (theta/pi) r, the "rotational velocity" would be (w/pi) r.