Can someone please explain to me the second law of thermodynamics?

Question

as well as it's relation to the first? and what's the point of the zeroth?

Answer 1

الله اكبر

1st:

dE = δQ + δA

2nd:

dE = TdS - PdV

Answer 2

The second law of thermodynamics is entropy (decay.)

Left to themselves, all things tend to fall apart.

A common example --  If you don't maintain a barn it will eventually fall down.

Answer 3

Good question!  I don't know the others very well; you might want to read them on Wikipedia, or maybe someone else will answer about them.  But I can give you the basics of the Second.

The Second Law of Thermodynamics states that, in a closed system, the amount of entropy will increase over time.  You may have heard of the Second Law from people arguing against evolution, on the grounds that it means a system can't become more ordered.  If that were true, refrigerators wouldn't work, and embryos wouldn't grow to become babies, toddlers, children, and finally adults.

First of all, the Second Law only applies to closed systems.  If you input energy into something (plug the refrigerator into the wall for instance), it's no longer a closed system.  The Earth isn't a closed system because it's powered by the Sun.

The other thing about the Second Law is the definition of entropy.  I don't understand entropy completely myself, but I do know that it's not actually a measure of disorder.  Entropy being equivalent to disorder is an analogy that's used in introductory courses to help students grasp the concept; it's not the definition of the word.  As I understand it, entropy deals with states of energy.  As energy goes from one state to another, it becomes either more or (more often) less useful.  For instance, the energy in a gasoline engine converts eventually into the least useful form of energy, heat.

If that seems a little anticlimactic, it's not too surprising.  I understand that the laws of thermodynamics aren't a huge part of physics, but they've gotten a lot of press from the creationist crowd.

Answer 4

2nd law of thermodynamic: An unopened thermos will lose heat proportionally to the size of the hole and the temperature outside

The first law just says that you should always replace the cork when using a thermos, or bad things will happen.

Answer 5

THe 2nd law states that heat cannot be transfer from a colder to a hotter body. As a result of this fact of thermodynamics, natural processes that involve energy transfer must have one direction, and all natural processes are irreversible. This law also predicts that the entropy (the measure of the disorder or randomness of energy and matter in a system.)  of an isolated system always increases with time.   Because of the second law of thermodynamicsof both energy and matter in the Universe are becoming less useful as time goes on. Perfect order in the Universe occurred the instance after the Big Bang when energy and matter and all of the forces of the Universe were unified.

hope these helps