$2-3.$ A pressure vessel, in the form of a cylinder wift hemispherical ends has a radius

of $2$ ft and is to be made from a metal whose $A=80$ksi. The maximum internal

pressure intended during use is $5$ ksi $.$ If no section of the vessel is to yield, what

minimum wall thickness should be specified according to: $($a$)$ the Tresca criterjon?

$($b$)$ the von Mises criterion?