[填空题]
A helicopter rotor blade ca s5yy:2 o6puran be consideredp6hbzi r) v1zuar8ic57wu0 j*-4lb m f a long thin rod, as shown in Fig. 8–46.u6)z bich14 lfu zi5bprva*7-0jm 8wr (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? $m \cdot N$