Mechanical Engineers: Help Designing a Solid Shaft

[lilMissMindset]

to my fellow mechanical engineers, please help me with some basic machine design problems.

a certain drive shaft rotating at 500 rpm transmits 200 hp to an 8 inch diameter gear. Design a suitable solid shaft for this application. the shaft is ductile. Design stresses are to be limited to σmax= 134 ksi and ζmax = 40 ksi

 

[SteamKing]

Is zeta max = 40 ksi supposed to be the limiting shear stress?

Anyway, figure out how much torque is to be transmitted by the shaft. Size the shaft using the max. torsional stress as a first cut.