# Angular velocity

1. Mar 12, 2006

### sauri

A merry-go-round is accelerated from rest by a child at a steady acceleration of 0.2 rad.s-2.

1)How long does it take for the merry go round to reach an angular velocity of 1.4 rad.s-1?
2)How many revolutions does the merry go round (and the child) make in this time?

I belive I worked out the first one, where a=w/t. so t=w/a (t=1.4/0.2). Am I correct?.

However I can't understand the second part..is there an equation to find the number of revs?

2. Mar 12, 2006

### phucnv87

The first question, I think you're right.
For the second one, find the angle $\theta=\frac{1}{2}at^2$
The revolutions are $N=\frac{\theta}{2\pi}$

3. Mar 12, 2006

### sauri

is it ok to use w=[itex]\theta/t to find the angle?

4. Mar 12, 2006

### Hootenanny

Staff Emeritus
No because this will only give you an average angular frequencey. As there is acceleration you need to use the equations phuncv87 posted.