A 2in-diameter steel propeller shaft of an experimental high-speed boat transmits 2500hp at 2000rpm. Bending and axial loads are negligible. a) What is the nominal shear stress at the surface? b)If a hollow shaft of inside diameter .9 times outside diameter is used, what outside diameter would be required to give the same outer surface stress? c) How do the weights of the solid and hollow shafts compare?