[填空题]
A helicopter rotor bsd0 bpks5psk)mt.:kgbl8 0n b:7am3jefy4:1d85dydkr my 4hq 8e gi7lade can be considered a long thin rod, as shown in Fig. 8–46 e45iry8m dkd :dfh8gqy4 1ye7. (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? $m \cdot N$