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1 Political Atheist  Wed, Oct 13, 2010 4:35:50pm

Bravo.

2 Mad Prophet Ludwig  Wed, Oct 13, 2010 4:37:28pm

re: #1 Rightwingconspirator

Bravo.

Thank you.

3 Dancing along the light of day  Wed, Oct 13, 2010 8:03:46pm

Awesome, and thank you for taking the time to do this!

4 b_sharp  Wed, Oct 13, 2010 8:06:18pm

Kudos my man.

The tangled string (or computer cords) is one of my favourite explanations.

Small quibble. It should be an isolated system not a closed system. A closed system restricts matter but not energy and heat transfer.

5 Mad Prophet Ludwig  Wed, Oct 13, 2010 8:31:28pm

re: #4 b_sharp

Kudos my man.

The tangled string (or computer cords) is one of my favourite explanations.

Small quibble. It should be an isolated system not a closed system. A closed system restricts matter but not energy and heat transfer.

No, it should be a closed system in this case. I was talking about pistons doing work.

Another statement of the second law which is equally useful comes from Kelvin.

No process is possible whose sole result is the absorption of heat from a reservoir and the conversion of this heat into work.

6 Mad Prophet Ludwig  Wed, Oct 13, 2010 8:39:00pm

re: #4 b_sharp

Kudos my man.

The tangled string (or computer cords) is one of my favourite explanations.

Small quibble. It should be an isolated system not a closed system. A closed system restricts matter but not energy and heat transfer.

Actually never mind, after re-reading what I wrote, you are correct.

7 Mad Prophet Ludwig  Thu, Oct 14, 2010 3:09:03am

re: #4 b_sharp

I clarified some of the language in that section. I think it reads better now.

8 mkelly  Thu, Oct 14, 2010 9:39:00am

Since you gave the first law in an equation here is the second law for those who enjoy equations. dS = dQ/T (T in Kelvins)

9 Mad Prophet Ludwig  Thu, Oct 14, 2010 10:36:03am

re: #8 mkelly

Since you gave the first law in an equation here is the second law for those who enjoy equations. dS = dQ/T (T in Kelvins)

Glad that you can Wiki...

Most people would have written dU = TdS - PdV. I was planning on getting into that in the next lecture.

So just out of curiosity, what does this equation mean to you?

I mean what you wrote: dS = dQ/T

I wouldn't pin you down except for your track record of utter ignorance with certain posts.

How would you derive this? Where did it come from?

What light does the Kelvin Statement shine when the first law is written as:

dU = TdS - PdV ?

The reason I didn't go into it this post is that the discussion of a larger or smaller heat difference and thermodynamic efficiency would have taken away from the main point I wanted to make about different micro states and information. Though in my discussion of temperature, I hinted at all the pieces for this view of Entropy.

Would you care to fill that in?

Now that you have decided to bring this, do please enlighten all of us.

To those who don't know MKelly, one of the more irrational climate deniers on this blog, and might be wondering why I am so hostile to him, I will simply say that his "argument" that AGW violated the first law of thermodynamics, was one of the inspirations for this whole series of writings.

10 MKelly  Thu, Oct 14, 2010 11:21:21am

re: #9 LudwigVanQuixote

Sorry LVQ I did not use wiki. If you disagree with the formula fine. Since I do not have a keyboard that allows > and = one on top to the other I just used =. It is what I remember from thermodynamics class and in a book by Dr. Linda Huetinck.

I put in parens Kelvin as I did not want folks to think of F when they say a T. Thats all.

I was not be critical only adding some info. Don't be to touchy. Overall I think this was a good job.

11 Interesting Times  Thu, Oct 14, 2010 11:31:40am

re: #9 LudwigVanQuixote

A Runaway Greenhouse Effect?

The atmosphere would finally stabilize at a still higher temperature and pressure after all the carbon dioxide had been driven from the rocks. In fact, we believe that if this sequence were to take place on the Earth, the resulting temperature and pressure of the atmosphere left behind would not be very different from that for present-day Venus: the atmospheric temperature would be hundreds of degrees Celsius and the pressure would be maybe 100 times greater than it is today.

Thus, we believe that in the case of Venus the initial solar heating kept oceans from forming, or kept them from staying around if they did form, and the subsequent lack of rainfall and failure of plant life to evolve kept the carbon dioxide in the atmosphere rather than binding it in the rocks as is the case for the Earth; thus, Venus has an environmental disaster for an atmosphere.

The sobering warning for us is obvious: we have to be extremely concerned about processes such as burning of fossil fuels in large volumes that might (we don't know for sure because the scientific questions are complex) have the potential to trigger a runaway greenhouse effect and produce on the Earth atmospheric conditions such as those found on Venus.

Exactly as I suspected - contrary to troll denier claims, it's not the "atmospheric pressure" on Venus that caused it to warm, but the exact opposite - the runaway greenhouse effect caused the heating which in turn made the atmosphere that dense and that thick.

12 Mad Prophet Ludwig  Thu, Oct 14, 2010 11:59:56am

re: #11 publicityStunted

A Runaway Greenhouse Effect?

Exactly as I suspected - contrary to troll denier claims, it's not the "atmospheric pressure" on Venus that caused it to warm, but the exact opposite - the runaway greenhouse effect caused the heating which in turn made the atmosphere that dense and that thick.

13 Mad Prophet Ludwig  Thu, Oct 14, 2010 12:00:21pm

re: #11 publicityStunted

great post btw.

14 b_sharp  Thu, Oct 14, 2010 7:00:45pm

re: #7 LudwigVanQuixote

I clarified some of the language in that section. I think it reads better now.

I bet you're a damn good Prof.

15 Mad Prophet Ludwig  Thu, Oct 14, 2010 7:14:09pm

re: #14 b_sharp

I bet you're a damn good Prof.

Thank you!


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