[填空题]
A helicopter rotor blade can be considered a long thin rod, as shown : /h3ds 4rgnnad r2z8hciq )-din o o2e8au l c84qmpq7wdv 7 7rw(yzl)c3Fig. 8–4o (ywa487p7qvz)oe8wu3 rl d2lmc q7c 6. (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? $m \cdot N$