# Homework Help: Units in Angular Velocity

1. Feb 22, 2014

### fluidmech

1. The problem statement, all variables and given/known data
Hello, I am doing a mechanisms homework assignment in which a hydraulic piston moves out and moves a link connected to the piston in an angular fashion. I'm just a bit confused about the units of angular velocity and I feel very foolish asking this.

2. Relevant equations
$$\omega \times r = v$$
$$\omega = \frac{v}{r}$$

3. The attempt at a solution
$$v=0.751751\frac{m}{s}$$
$$r=0.6 m$$
$$\omega=\frac{v}{r}=\frac{0.751751 \frac{m}{s}}{0.6 m} = 1.25 \frac{rad}{s}$$

Can someone just double check that the units are indeed radians per second? SI units for angular velocity is rad/s.. and this is SI. Just want to double check that it's not rev per second. I know, it's foolish. Thanks in advance!

2. Feb 22, 2014

### Dick

Yes, it's radians/sec. rev/sec differs by a factor of 2pi. To convince yourself, if v=1m/sec and r=1m and the motion is circular then v/r=1/sec but it would take you 2pi seconds to get around the whole circle and make a rev.

Last edited: Feb 22, 2014