Consider the implications of the energy balance AU + AEK + AEp = Q + W for a closed system. Adiabatic System For an adiabatic system with negligible changes in potential and kinetic energy, positive work done by the system on the surroundings implies change in internal energy of the system. Acceleration A system with positive acceleration has a . Hint negative positive zero Save for Later Kinetic and Potential Energy If only changes in kinetic and potential energy are permitted, then a falling object under the influence of gravity must travel at a constant speed slow down speed up Condensation In the absence of any kinetic or potential energy changes and any work, a system composed of condensing steam requires that Q be Adiabatic System For an adiabatic system with negligible changes in potential and kinetic energy, positive work done by the system on the surroundings implies change in internal energy of the system. Conservation If Q = W, then Hint the internal energy is constant the system is insulated the system is isolated the total energy of the system is constant Save for Later Piston/Cylinder For the system of an expanding cylinder/piston assembly and contents providing work to a generator, Wis Hint positive zero negative