QUESTION I: Basics, Work, First Law for fixed mass $(25$ Marks$)$

a$)$ Briefly explain the thermodynamic terms listed below. $($You may use a sketch, equation, or example as an aid if you wish.$)$:

$($i$)$ State;

$(2$ Mark$)$

$($ii$)$ Closed System;

$(2$ Marks$)$

$($iii$)$ Heat Engine;

$(2$ Marks$)$

$($iv$)$ Adiabatic Process.

$(2$ Marks$)$

b$)$ A certain fluid expands reversibly in a sealed cylinder from initial conditions of $9$ bar $($ABS$),1m^3$ to $7m^3$ according to Boyle's Law $PV=C.$ Show the process on an appropriate graph. Calculate the thermodynamic work and the final pressure.

$(11$ Marks$)$

c$)$ The fluid in b$)$ above is cooled at constant pressure until the volume piston volume returns to $1m^3.$ It is then heated at constant volume until the pressure returns to $9$ bar $($abs$).$ Calculate the net work of the cycle and explain whether the cycle is a heat engine or reversed heat engine.

$(6$ Marks$)$