Encyclopedia of Science

[CynthiaA]

The First Law of Thermodynamics I understand. It makes sense, not a problem.

The Second Law of Thermodynamics I thought I understood, but now after considering it more, it is not truly making sense. There was an example given to illustrate the Second Law of Thermodynamics which had a rock in the hand of a person who dropped the rock. The idea being as the rock drops toward the ground it creates entropy.

Well, the rock cannot create the entropy. It is the force behind the rock that creates the entropy, right? And is that force the hand dropping the rock or gravity or both?

Perhaps I am a little confused. Can someone please explain?

Thank you,
Cynthia

[CynthiaA]

Well considering it more, it would be the combination of all of them. The mass of the rock, the force of gravity, the hand releasing the rock, time, and velocity. Right?

[CynthiaA]

I found my answer!

[Yac]

So share with me and other readers.

[CynthiaA]

Thank you, Yac for asking!

It seems like to me that the second law of thermodynamics was written to complete the first law of thermodynamics, so my first thought was all of the laws of thermodynamics are dependent on each other and should be taken as such.

It also seems like all of the laws of thermodynamics work globally together within a system. What is so way flippin cool about thermodynamics is the applications are not limited to any one specific system. I mean, they apply to jet propulsion just as easily as they apply to time or quantum computing. Basically, I guess any system that deals with energy and the processing of energy (some people say, "work" in place of processing of energy).

The Second Law of Thermodynamics establishes heat (energy) can only transfer to a cold state.

I guess this is where entropy comes into the system image. I LOVE entropy. Entropy is the process of energy spreading out and loosing its density. Of course entropy is dependent on the type of system it is occurring within.

Isolated systems do not exchange matter or energy within their surroundings and entropy is the same during any reversible process, but increases during nonreversible processes.

In Non-Isolated systems, entropy is dependent on temperature fluctuations and surroundings. The amount of energy that enters and leaves the system will also have an affect on entropy.

It makes perfect sense.

The third law addresses entropy in relation to changes in temperature.

That is why I think they are all a part of each other. I guess they would have to be because they refer specifically to the energy and work of a system. A system is many parts with many functions.

I found this great definition: There exists a useful thermodynamic variable called entropy. A natural process that starts in one equilibrium state and ends in another will go in the direction that causes the entropy of the system plus the environment to increase for an irreversible process and to remain constant for a reversible process.

In truth, I still do not get the rock example. I mean there does not seem to be any entropy involved, no heat exchanged. The only thing I can come up with about the rock is maybe the wave in the air as it falls, or perhaps the events in the world line pertaining to time. I truly do not know.

Thanks again, Yac!

Cynthia

[CynthiaA]

Eureka! I got the rock thing!


The Second Law of Thermodynamics (SLOT) is as described in the previous post; hot to cold.

It also represents downward movement, as in the hand is suspending the rock. It allows the rock to fall downward toward the ground. Because the rock is falling downward and not upwards (LOL at that image) it is experiencing the SLOT!

Batteries run down, lightbulbs burn out, you get the idea.

Now how way flipping cool is that?

Cyndi

[CynthiaA]

The Zeroth Law

The Zeroth Law states:

If object A is in thermal equilibrium with object B, and object B is in thermal equilibrium with object C, then object C is also in thermal equilibrium with object A.

This Law allows, among other things, the creation and calibration of thermometers.



This law is sometimes referred to as the Fourth law of Thermodynamics. It was overlooked, but when scientists were considering the other three laws of Thermodynamics they realized this law was needed and it should have been first. So they determined to call it The Zeroth Law and place it in front of the First Law of Thermodynamics.

I thought I would post it because I did refer to the other three and it seemed appropriate to include the Zeroth Law as well.

C

[gullyfourmyle]

How about considering the following:

How far the rock is falling

Where the rock is falling from

What the rock is falling through

[CynthiaA]

[quote="gullyfourmyle"]How about considering the following:

How far the rock is falling

Where the rock is falling from

What the rock is falling through[/quote]

In relation to the Second Law of Thermodynamics, how far the rock is falling is not as important as the rock is falling down in direction. The second law states a downward movement.

Where the rock is falling from could have some significance in that the rock is attached to the side of a mountain trying to fall to sea level (a downward movement). Not strongly significant, but could play a role in establishing the downward direction.

Hmmm...falling through, only if it affected the temperature of the rock as the second law of thermodynamics specifically states hot to cold, but not cold to hot. Perhaps whatever the rock were falling through might slow the cooling process or affect the speed in which the rock fell. It would not make the rock fall in an upward direction.

Thanks Gullyfourmyle, for asking!