I was watching a video from mitocw in which the professor wrote that:
dU = dw(reversible)
If we consider a free expansion, then the work done must be 0. The process is also adiabatic implying that heat transferred must also be 0.
Now we know that Temperature of the gas would change (as pressure would decrease) but the change in the internal energy would be 0. The fact that temperature is changing without bringing about a change in internal energy is something i am unable to understand.