What literary translation is given to the notation : $c_{v}$ and $c_{p}$?
c: specific heat capacity.
v, p index : at constant volume, pressure.
What is the use of adding the same symbol in the right member of the equation!.
PS: when you 'pour' physical or mathematical ideas into a 'symbolic mold', it must express (contain) all the ideas, a good nation facilitates the comprehension and avoids the useless clutter what makes understand Alexander Grothendieck to its students from the beginning .