1. The problem statement, all variables and given/known data Is it possible to have a process that is both adiabatic and isothermal. 2. Relevant equations 3. The attempt at a solution I think the answer is no. Because when a system is doing an adiabatic process, the total energy of this system must be changed. For an adiabatic process, there is no heat transfer to or from the system. So the temperature of the system must be changerd. But, an adiabatic process only means that there is no heat transfer to or from out side. So when the out side environment is doing work on the system and the system transfer whole work out of itself. the temperature of the system will be same. but i am not sure is this ture. could somebody explane this for me? Thanks.