[填空题]
A helicopter rotor bz5gr. a 1tbz*+ ve6l apqunu73ladeo t2ig):rrc *d yvn..j,:on1m5asiwb can be considered a long thin rod, as shown in Fig. 8–4.a.vt1:bydn mg,r* ii : osrwc25onj)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? $m \cdot N$