[填空题]
A helicopter rotor blade can bih8il7 oo0)f; 0nctsle considered a long thin rod, as shown in es pg 7ib7s739 (dlnumFig. 8–46.3isunp 9lg em 77bd7(s (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? $m \cdot N$