Power from a 3200 hp motor is transmitted by a 2 1/2 in diameter shaft rotating at 2000 rpm. Bending and axial loads are negligible. a) What is the nominal shear stress at the surface? b) If a hallow shaft of inside diameter 0.85 times outside diameter is used, what outside diameter would be required to give the same outer surface stress? c) How do weights of the solid and hallow shafts compare?