chap 15

• adiabatic process a process in which no heat transfer takes place
• Carnot efficiency the maximum theoretical efficiency for a heat engine
• Carnot cycle a cyclical process that uses only reversible processes, the adiabatic and isothermal processes
• Carnot engine a heat engine that uses a Carnot cycle
• change in entropy the ratio of heat transfer to temperature
• coefficient of performance for a heat pump, it is the ratio of heat transfer at the output (the hot reservoir) to the work supplied; for a refrigerator or air conditioner, it is the ratio of heat transfer from the cold reservoir to the work supplied
• cyclical process a process in which the path returns to its original state at the end of every cycle
• entropy a measurement of a system's disorder and its inability to do work in a system
• first law of thermodynamics states that the change in internal energy of a system equals the net heat transfer into the system minus the net work done by the system
• heat engine a machine that uses heat transfer to do work
• heat pump a machine that generates heat transfer from cold to hot
• human metabolism conversion of food into heat transfer, work, and stored fat
• internal energy the sum of the kinetic and potential energies of a system’s atoms and molecules
• irreversible process any process that depends on path direction
• isobaric process constant-pressure process in which a gas does work
• isochoric process a constant-volume process
• isothermal process a constant-temperature process
• macrostate an overall property of a system
• microstate each sequence within a larger macrostate
• Otto cycle a thermodynamic cycle, consisting of a pair of adiabatic processes and a pair of isochoric processes, that converts heat into work, e.g., the four-stroke engine cycle of intake, compression, ignition, and exhaust
• reversible process a process in which both the heat engine system and the external environment theoretically can be returned to their original states
• second law of thermodynamics heat transfer flows from a hotter to a cooler object, never the reverse, and some heat energy in any process is lost to available work in a cyclical process
• second law of thermodynamics stated in terms of entropy the total entropy of a system either increases or remains constant; it never decreases
• statistical analysis using statistics to examine data, such as counting microstates and macrostates