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 g?

Solution 26E If is the rotational speed and r is the radius of the the path of circular motion then the linear speed of the speed of the particle is given by v = r Step 1 In the given problem we have = 550 rev/min = (550 rev/min)(2 rad/rev)( 1 ) = 57.6 rad/s 60 s/m And the radius of the path of the tip is r = 3.10 m So the linear speed is v = (57.6 rad/s)(3.10 m) = 179 m/s