Shock wave formation.

[Pugilistic Animus]

The First Law

This has been a hard one for me cuz---I'm skipping special maths---{energy is the capacity to move stuff against a force [i.e do work]

The change in internal energy-Ef-Ei---a State function

The change in internal energy---is independent of path, but is composed of path functions--and for simplicity [in aerothermodynamics one excludes such paths as electrical work ] ---and IE is independent of volume perfect gases----

dE = Q[heat] + W [work] [both path functions]---

Assuming only adiabatic [no heat lost or gained] expansion work W = - Pex dV [look at the units]----then dE=w=-Pexdv


--the heat capacity [Cp] at constant pressure is equal = dH= dQ+Vdp[p=constant] so dH=dQ

and dE=CvdT [q=0] so [Work] adiabatic=Wad, but because of path independence ---I can say that dE [due to Wad] = work done isothermally---or electrically--if you want [dE=STATE function]

so CvdT [Wad]=-Pdv [isothermal work]


that's enuf--for me too---but I'll continue this it's a not easy to explain this ---any questions so far?

PA