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.

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