Finding the angular displacement

1. Aug 12, 2004

Schu

Here's the question:
the rotor of a helicopter starts from REST and reaches it's operating speed in 7.28s If the angular acceleration of the rotor is 92.5 rad/s^2, what is the angular displacement during that time?

I'm not sure where to start.
If I multiply the time by the acceleration I would get the velocity only in rad/s.
But then I was thinking more like:
Angular position= 1/2 (angular acceleration) *t^2+(initial angular velocity)*t+(initial angular position)

If I plug them into the angular position formula I get 2451.176 rad

Is the angular displacement a fancy way to say angular position??
Is this the right track to be on?

2. Aug 12, 2004

arildno

It's definitely the right track!
(displacement=new position minus old position, so by assuming old angular position 0, the angular displacement equals the new angular position)