[填空题]
A helicopter rotor blavkuuzqa z)yx; 4:kne2 +3n/xzde can be considered a long thin 4( p7yvky95 p 2j*)jb(m+rv gsepkfgyrod, as shown in Fig. 8–46.gspy(j)v 4pb5 y9k e m fj2+rkpg*v7y( (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? $m \cdot N$