physics
posted by Kelly .
A model of a helicopter rotor has four blades, each 3.40 {m} in length from the central shaft to the tip of the blade. The model is rotated in a wind tunnel at 580 {rev/min}. What is the radial acceleration of the blade tip, expressed as a multiple of the acceleration g due to gravity?

I assume you mean that the blades are rotated at that rate, not the model itself.
blade angular velocity:
w = 580*2*pi/60 = 60.7 rad/s
Radial acceleration of tip = R*w^2
= 1.25*10^4 m/s^2
Divide by 9.8 for g's.