L.3 - Energy Flashcards
What is the first law of thermodynamics?
energy cannot be created or destroyed, it can only be transformed from one form to another
What is the second law of thermodynamics?
as energy is transferred or transformed, there is always some inefficiency/waste
Define Work:
product of force an displacement
Define Energy:
capacity of doing work
Define Power:
rate of doing work
What is the difference between an open and a closed system?
- in an open system energy and matter are allowed to flow through REV boundary
- in a closed system, only energy but not matter are allowed to flow through REV boundary
Define Total Energy:
sum of microscopic and macroscopic forms of energy (internal & external “PE”,”KE”)
Define Kinetic energy:
external energy caused due to movement
Define Potential Energy:
external energy caused to a change in position
Define Internal Energy:
energy that is part of the molecular structure of a given substance
Define External Energy:
energy due to location of movement of a substance
What is specific heat/ heat capacity of a material?
its ability to store energy
Define heat capacity:
the amount of energy required to raise the temperature of a mass m by delta T
Define Enthalpy of Fusion:
energy required to cause a phase change in a unit mass from solid ti liquid
Define Enthalpy of Vaporization:
energy required to cause a phase change in a unit mass from liquid to vapour at constant pressure
What is Latent Heat?
it is related to changes in phase between liquids, gases, and solids
What is Sensible Heat?
related in changes in temperature of a liquid, solid, or gas with no change in phase
Where does the heat waste go (2nd law)?
the losses are energy converted to low-quality energy or less useful low temp. energy (1st law maintained)
What is Entropy?
measure of unusable energy within a system (as unuesable energy inc., entropy, inc., randomness and chaos inc.)
What are the forms of heat transfer?
1) Conductive
2) Convective
3) Radiation
Define Conduction:
the transfer of heat energy from one atom to another within a substance (has to be in contact)
Define Convection:
the transfer of heat energy by movement of currents
Define Radiation:
electromagnetic waves that directly transport energy through space
