[填空题]
A helicopter rotor blade can be considered a lo0ybe +w4ubp*u ng thin rod, as sh0prp d:g f)6mhown in Fig. 8–466gpf mdph ):r0. (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? $m \cdot N$