why the internal energy is 0 in case of isolated system? I mean, how the dq and dw are both 0

Question

anonymous · Answer

In an isolated system, dQ and dW are zero because there is no change in heat or work.

anonymous · Answer

how no change in work...i can understand that dq is 0..but please explain that hoe dw is 0

anonymous · Answer

given$$W=\delta E_k=1/2*m*(v_2^2-v_1^2)$$as there is no external force (heat, pressure, etc.) the average velocity of the atoms will not change (some might speed up or slow down as they hit each other, but the average stays the same).

anonymous · Answer

this is the best explanation i have got...thanks for mending my concept

anonymous · Answer

It's what I do ;)

anonymous · Answer

What you mean it say is the the change in energy is zero for an isolated system, and that heat and work must both appear at the boundary of a system, because by definition they measure flows of energy across the boundary.