1. The problem statement, all variables and given/known data When a sealed Thermos bottle of hot coffee is shaken, what changes, if any, takes place in the temperature of the coffee and its internal energy? Justify your answer. 2. Relevant equations Internal energy = random kinetic energy + random potential energy 3. The attempt at a solution The answer given says that because work is done on the system there is an increase in internal energy. But isn't the work done used to increase the mechanical energy of the system, not the internal energy. There should be no increase in the temperature, shouldn't it?