MOD 3 LECTURE 4                        LAWS OF THERMODYNAMICS

In this lecture you will learn:

Read thru the lecture and then click HERE for a most unusual convergence of science and pop culture

"Energy can neither be created nor destroyed." 

The total amount of energy in the universe is constant.  Energy cannot be created nor destroyed; it can merely be changed from one form to another. This also means that matter can neither be created nor destroyed. Basically, we got what we got, and that's all we're going to get.

Everything needs energy input to keep going. 
Energy can be internal or "stored" energy. 
Energy can change "form".  Ex: Potential <-> Kinetic
At each change in form of energy there is some energy lost as heat.  There is no perfect transformation of energy. 
->  There are no perpetual motion machines 
(i.e. machines that keep going forever w/o energy)

  "You can't get something for nothing"


 "Energy systems have a tendency to increase their entropy or randomness" 

· In any transfer of energy from one form to anther (for example, electrical to mechanical energy), useful energy is lost.  Basically, you can't get out more than you put in, and you can't even come close to getting out what you put in.

 The entropy (randomness) of a system will always increase, and it's impossible to decrease entropy without work.  Basically, heat and energy tend to migrate from areas of higher concentration to areas of lower concentration, and it requires work to get it to go the other way.

Ex: dust on furniture. Wiping it off requires energy, but when the dust cloth is shaken, dust returns to randomness.

"You can't even come close to getting something for nothing" or, "you cant break even"


"As temperature approaches absolute zero, the entropy of a system approaches a constant minimum." 

In brief, this postulates that entropy is temperature dependent and leads to the formulation of the idea of absolute zero. 
Ex: the entropy of a pure crystal will be zero at zero Kelvin (absolute zero).
HOWEVER, temperatures of 0oK can never be achieved - quantum mechanics prohibits it.

“you can’t get out of the game” !

(submitted by kelly.brutto)