[填空题]
A helicopter rotor blade can be considered ae;vnu qj5 iw(: long thin rod, as shown in Fig. xtx4sx59hin-pe n6.vi3s 1z m8–46. txp.nhxz6snv4i195 me- x i3s (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? $m \cdot N$