Enerrgy can transfter from syetm to surroundings as work if

Energy can transfer from system to surroundings as work if

What are the heat (q) sign conventions when heat is transferred from the surroundings to the system and that transferred from system to the surrounding?

Work done by the system on surroundings is :

No heat is absorbed by the system from the surroundings, but work (w) is done on the system. What type of wall does the system have?

Work done by the system on surrounding is

When no heat is absorbed by the system them from the surroundings, but work (w) is done on the system, the change in internal energy of the system is given as