A model of a helicopter rotor has four blades, each 3.40 m long from the central shaft

Question:

A model of a helicopter rotor has four blades, each 3.40 m long from the central shaft to the blade tip. The model is rotated in a wind tunnel at 550 rev/min
(a) What is the linear speed of the blade tip, in m/s?
(b) What is the radial acceleration of the blade tip expressed as a multiple of the acceleration of gravity, g?