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. (For each answer, enter a number.) (a) Calculate the magnitude (in m/s ) of the centripetal acceleration at the tip of a 3.50 m long helicopter blade that rotates at 255 rev/min. m/s2 (b) Compare the linear speed of the tip with the speed of sound (taken to be 340 m/s). Vtip sound