[填空题]
A helicopter rotor blade vt:f m xsnm9-m ko2-j.can bvwk0 m -a/u gpexli4(wncx+1 e2ha4h0e considered a long thin rod, as shown in Fig. 8–46.i+ ueawhg4n-p(m a0/ ew2xcl 4v10khx (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? $m \cdot N$