# Simple rotational mechanics

1. Apr 20, 2010

### crybllrd

1. The problem statement, all variables and given/known data
If a CD makes 1500 revolutions in 5 minutes, what is the CD's average rotational speed (in units of rad/s)

2. Relevant equations

$$\omega = \frac{\Delta\theta}{\Delta t}$$

-or-

$$\omega = \frac{2\pi}{\Delta t}$$

3. The attempt at a solution

This problem seems a little too simple (and I didn't use the given equation), so I want to make sure I did it right:

$$(5min)(60s/min)=300 seconds in 5 minutes$$

$$\frac{1500rev}{300s}=5rev/s$$

Last edited: Apr 20, 2010
2. Apr 20, 2010

### tvavanasd

You didn't answer the question; how many radians are there in one revolution?

3. Apr 20, 2010

### crybllrd

$$\frac{300s}{1500rev}=.2s/rev$$

$$\frac{2\pi}{.2}=31.4rad$$