phys_THERMODYNAMICS

Thermodynamics

the study of processes in which energy is transferred as heat and as work

Q + W

system

any and all objects which we are considering

open system

system that can exchange mass or energy with its environment

closed system

no mass enters or leaves this system

isolated system

no energy of any form enters or leaves this system

*nothing happens

First law of thermodynamics

statement of the conservation of energy. If a system exchanges heat or work with its environment, then its internal energy will change.

isothermal process

temperature is constant

isobaric process

pressure is constant

isochoric

= isovolumetric

volume is constant

adiabatic process

no heat flow

isotherms

curves at constant temperature on a PV diagram

heat engine

a machine that gets work from thermal energy

operating temperatures

temperatures of hot and cold sources of a heat engine

efficiency

useable work:: heat input into the engine

Carnot engine

ideal engine of ideal efficiency

reversible process

ideal process in which every moment may be considered equilibrium - definition of Carnot engine

second law of thermodynamics

* to explain why thermal E isn't transformed into K

The total entropy of an isolated system can never decrease. It can only stay the same or increase.

Entropy

measure of the disorder or randomness of a system