nozzle when the back pressure is $5\mathrm{.}283$ bar.

Example $10\mathrm{.}2$ A fluid at $6\mathrm{.}9$ bar and $93C$ enters a convergent nozzle with negligible velocity, and expands isentropically into a space at $3\mathrm{.}6$ bar. Calculate the mass flow per square metre of exit area:

$($i$)$ when the fluid is helium $(c_p=5\mathrm{.}19k\frac{J}{k}gK)$;

$($ii$)$ when the fluid is ethane