1. The problem statement, all variables and given/known data a) Liquid is stirred at constant volume inside a container with adiabatic walls. The liquid and container are regarded as the system. Is heat being transferred to the system? Is work being done on the system? b) Water inside a rigid cylindrical insulated tank is set into rotation and left to come to rest under the action of viscous forces. Regard the tank and water as the system. Is any work done by the system as the water comes to rest? Is there any heat flow to or from the system? 2. Relevant equations First Law of thermodynamics 3. The attempt at a solution I think I have the correct answers but I want to check my reasoning for each case: a)Work is being done on the system. The stirring produces a mechanical exchange of energy to the water. No heat flow since the walls are adiabatic. I think you could also say given that the stirrer is in contact with the water, after a time, no object is hotter than the other so this may not be regarded as heat transfer. b)'left to come to rest' implies no work is done by the water. The water comes to rest solely by the viscous forces which act as a retarding force to the rotational motion of the water. No heat transfer because the system is insulated. Are these ok responses?