$2-8.$ A thin$-$walled tube with closed ends is made from a metal whose $Y=40$ksi

The tube is $8$ ft long, has a wall thickness of $0\mathrm{.}050$ in $.,$ and a mean diameter o

$3$ in $.$ In service, the tube will experience a maximum axial tensile load of $2000$ lbf

a maximum torque of $2000$ lb $-$in$.,$ and will also be pressurized internally. Wha

minimum internal pressure will cause yieiding according to: $($a$)$ the von Mise

criterion?

$($b$)$ the Tresca criterion?