Question

While waiting to board a helicopter, you notice that the rotor's motion changed from 340 rev/min to 265 rev/min in one minute. Assuming that this acceleration remains constant, calculate how much longer (in seconds) it will take for the rotor to stop.

Answer 1

a = dv/dt = (265-340)/60 = -1.25 rev/sec

v = Vi + a t
0 = 265 - 1.25 t
t = 212 seconds