Consider a pressure vessel made by welding together two hemispheres of radius 20 ft and wall thickness 1.5 inches. If the allowed normal stress is 90 ksi, calculate the maximum allowed pressure within the spherical vessel. [For this problem do not include factor of safety.] Now design a cylindrical pressure vessel 20 ft long with flat circular end caps with the same wall thickness steel and containing the same volume as the sphere. Show the dimensions you have selected. If the allowed normal stress is 90 ksi, calculate the maximum allowed pressure within the cylindrical vessel.