[填空题]
A helicopter rotor bl4h2 r,g)yzmmp0)yjx t66uv gvn v2w-u ade can beo8sg2y0)i u d ert9ny/ considered a long thin rod, as shown in Fig. 8–46ngte2yy8di0os/ r)u 9 . (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? $m \cdot N$