[填空题]
A helicopter rotor blade can be considere1bkm dp a 3jz+)bmo8qip-;4w77hyyfp d a long thin rod, as shown ie fh57jdu*.55 ckkp tcn Fig. 8–46*tp5d5c5. hkcfe7u jk. (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? $m \cdot N$