[填空题]
A helicopter rotor bladj*av yajk2 xm -ys1v;,e can be considered a long thinpco i 6s3 7mdbc6o;,u0af0lzm rod, as shown in Fig. 8–4los,u cf;c6d 0mm 36bzi70o pa6. (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? $m \cdot N$