[填空题]
A helicopter rotor blade cajv4nguwr0i *t sgjb n-((0)nsn be consizha* j +nxxi/q1u8r pyy;:h.xdered a long thin rod, as shown in Fig. 8–46.a.uxi:; xyqzp r*nxh+ 8h y/j1 (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? $m \cdot N$
