Problem $3(40$ points on $100-$point scale$)-$ Helium is heated as it flows through a $6$ in$-$by$-6$ in

square duct with negligible friction. At the inlet, helium is at $T_1=700R,P_1=80$ psia, and $V_1=$

$260f\frac{t}{sec}.$ Determine the rate at which heat must be transferred to the air to choke the flow at

the duct exit. Note the working fluid is helium, not air.

PLEASE ALSO ADD ASSUMPTIONS!!