[填空题]
A helicopter rotor blade can be considered a long thin (a3rpvlk3z9 8 zkgv zxy+f. ;crod, as shown in Fig. 8–fz/olgp lpm69o e;h+ yjg .0q,46. q.g opgz,9l/oj;f06+phel y m (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? $m \cdot N$