[填空题]
A helicopter rotor blade ii,p9i1)h q9ixtnow )can be considered a long thin rod, as shown in fd7 s*anwlfe sk9)96c Fig. 8–4a 9e w)*sfndcs k96l7f6. (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? $m \cdot N$