energy can be stored within systems in three forms: internal energy, kinetic energy, and gravitaional potential energy

energy can be transferred to and from closed systems only by work and heat transfer

energy transfer by heat to and from a system is due to a temperature difference between the system and its surroundings

types of heat transfer

• conduction - transfer of energy from more energetic particles of a substance to adjacent less energetic particles

• radiation - energy transported by electromagnetic waves (does not need contact)

• convection - energy transfer between a solid surface at a temperature and and adjacent gas or liquid at another temperature

sign conventions for work and heat transfer

First law of thermodynamics - energy is conserved

energy balance

energy rate balance

Key Terms and Concepts

• internal energy - all other energy of a system which is not related to position (potential) or motion (kinetic)

• adiabatic process - a system undergoes a process involving no heat transfer with its surroundings

• heat and energy are not properties (not only reliant on the initial and final states of a process)

• thermodynamic cycle - a sequence of processes that begins and ends at the same state