[填空题]
A helicopter rotor blade c/h7d;f2kf ;zbxz9e lpan be considered a long thin rod, as shown in Fig. e;9,obi yx163exhwqb8–4i1b,w qyex9ho b6e;x36. (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? $m \cdot N$