[填空题]
A helicopter rotor blade can be considered a long thhf6s3qd,j, l ain rod, as shown in wazizx;8ids n5;tz6)p8*.3z t vajjh Fig. 8–46dw .vzi siz;58)aa 3pzt*nth8xj6j;z. (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? $m \cdot N$