[填空题]
A helicopter rotor blade can be considered a long thin rodu6khx.e.tg f :se o7f7, as shown inzocbbwt9aw,,yh/ c9 , Fig. 8–46.yza,9 9b,,cobtcw/ h w (a) If each of the three rotor helicopter blades is 3.75 m long and has a mass of 160 kg, calculate the moment of inertia of the three rotor blades about the axis of rotation. $kg \cdot m^2$ (b) How much torque must the motor apply to bring the blades up to a speed of 5 $rev/s$ in 8.0 s? $m \cdot N$