please I need clarification about the first principle of thermodynamics, it's general statement is:
$$\Delta U + \Delta \text{KE} + \Delta \text{PE}= W + Q .$$
Supposing that: $ΔU = 0$ and $Q = 0$, then: $\Delta \text{KE} + \Delta \text{PE}= W$ (of total forces).
But, We know from classical mechanics that :$\Delta \text{KE} + \Delta \text{PE}= W$(of non conservative forces)
We get : $W$(of non conservative forces)$= W$(of total forces)
WHICH IS ABSURD!
Nothing is absurd here.
When writing $$\Delta U+\Delta \text{KE} +\Delta \text{PE}=W+Q$$ the work term $W$ is work done by non-conservative forces as well as work done by any external conservative forces you haven't included in $\Delta \text{PE}$. This is also true in your "classical mechanics" expression $$\Delta \text{KE}+\Delta \text{PE}=W$$
The $W$ here is not "net work done by all forces". This is only the case in your "classical mechanics" sense using the work energy theorem of $W_\text{net}=\Delta \text{KE}$. Where now you are talking about the work done by all forces.
So, really you have "W(of non conservative forces)= W(of non conservative forces)" which, of course, is fine.
