1. The problem statement, all variables and given/known data A Chinook helicopter’s rotor blades and hub have a top speed of 300 revs/min and a combined mass of 300 kg. On a maintenance test the blade assembly is allowed to stop without applying the brake, in this condition the blades take 48 seconds to come to a standstill. The effective radius off the rotor is 6.8 m. I need to calculate the following: a. The deceleration of the rotor blades, assuming a constant rate of deceleration. b. The number of turns the rotor assembly will make. c. The frictional resistance at this deceleration. 2. Relevant equations 3. The attempt at a solution I have completed the first two parts: 300 rev/min * (2pi)/60 = 31.416 rad/s Acceleration = (ω2 - ω1)/(t2 - t1) = (0-31.416)/(48) = -0.6545 rad/s^(2) ϴ = ω1 * t + 1/2 * a * t^(2) = (31.416*48)+(0.5x(-0.6545)*48^(2)) = 753.984 rads 753.984/(2pi) = 120 revolutions For the final part, all I have came up with so far is that the friction will be acting downwards as a result of gravity, F = mg = 300*9.81 = 2943N I'm not sure if this is the right thing to do though, as the question asks the friction 'at this deceleration', so I guess I need an equation that contains acceleration in it. Thank you for any help! EDIT: Do I need to use the equation: Frictional torque = angular acceleration * Inertia?