# Homework Help: Need help finding revolutions?

1. Sep 22, 2009

1. The problem statement, all variables and given/known data

As their booster rockets separate, Space Shuttle astronauts typically feel accelerations up to 3g, where g = 9.80 m/s2. In their training, astronauts ride in a device where they experience such an acceleration as a centripetal acceleration. Specifically, the astronaut is fastened securely at the end of a mechanical arm that then turns at constant speed in a horizontal circle. Determine the rotation rate, in revolutions per second, required to give an astronaut a centripetal acceleration of 2.89g while in circular motion with radius 9.46 m.

2. Relevant equations

v= 2(pi)(r) / T

3. The attempt at a solution

28.322 m/s^(2) = v^(2) / 9.46m

v= 16.368

T= 2(pi)(9.46m) / (16.368) = 3.631

Is that right???

2. Sep 22, 2009

### rock.freak667

you want to find the angular velocity ω. So use v=rω and find ω.

Alternatively you could have used another expression for centripetal acceleration

a=ω2r