a uniform helicopter rotor blade is 7.8m long , has a mass of 110kg, and is attached to the rotor axle by a single bolt . A) what is the magnitude of the force on the bolt from the axle when the rotor is turning at 320 rev / min . ( hint : for this calculation the blade can be considered to be a point at its com . why ? please answer this as well ). B) calculate the torque that must be applied to the rotor to bring it to full speed from rest in 6.7 s . ignore air resistance . ( the blade cannot be considered to a point mass for this calculation . why not ? assume the mass distribution of a thin uniform rod . ) (C) how much work does the torque do on the blade in order for the blade to reach a speed of 320 rev / min . ?? any help is appreciated .