A model of a helicopter rotor has four blades, each of length 3.30 m from the central shaft to the blade tip. The model is rotated in a wind tunnel at a rotational speed of 590 rev/min .a. What is the linear speed of the blade tip?
b. What is the radial acceleration of the blade tip expressed as a multiple of the acceleration of gravity?

a) 195.82m/a

b) 1149.7g

Explanation: parameters given are:

angular velocity, ω 

= 550 rpm

Convert rev/ min to rad/s

= 550 * 2π /60

= 55π/3 radians/s

radius, r = 3.4 m

A. 

Using linear speed formula

Linear speed, v

= r ω m/s

= 3.4 * 55 π/3 m/s

= 195.83 m/s

B.

Let use acceleration derives from centripetal acceleration

a = v^2/ r

This lead to

radial acceleration

= r ω2

= 3.4 (55π/3)2 m/s/s

= 11279 m/s/s

Acceleration due to gravity g = 9.81m/s^2

Expressing as a multiple of g gives

= 11279 / 9.81 g

= 1149.7 g

hi there!

out of the two, (b) precision would be more reasonable.   however, both a and b could be pretty reasonable.

-awesomerepublic   : )