Key Takeaways

KEY TAKEAWAYS

• The first law of thermodynamics states that the change in internal energy of a system is the difference between the heat put in and the work output of the system.

• Heat energy into the system is positive and work energy out of the system is positive.

• There are adiabatic, isothermal, isochoric, and isobaric processes involved in energy systems.

• The work done is the area bound by a pressure-volume curve in an engine.

• Heat always goes from hot to cold areas in a system.

• A Carnot engine involves a theoretical engine in which the processes are always reversible.

• The second law of thermodynamics applies also to the fact that entropy is always increasing or held constant.

• In order to decrease the entropy of a system, energy must be put into it from an external source.