Helicopter blades withstand tremendous stresses. In addition to supporting the weight of a helicopter, they are spun at rapid rates and experience large centripetal accelerations, especially at the tip. Calculate the centripetal acceleration at the tip of a 3.90 m long helicopter blade that rotates at 250 rev/min.

Compare the linear speed of the tip with the speed of sound (taken to be 340 m/s), i.e., calculate the ratio of the linear speed over speed of sound.