[填空题]
A helicopter rotor blade cans3tf)y-p c po; be considered a long thin rod, as shown in Fig. b+8s3 hvt+vnws4f qoz )gx8o2 8–46. +o+v shgvqsb n)xft3z 2o848w (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? $m \cdot N$