Tuesday, April 16, 2013

The Thermodynamics of Menopause


Kellie’s hot flashes continue unabated, repeating every 45 minutes as they have done for the past three years. That’s like getting burned at the stake 35,000 times. Each attack turns her into a hot, sweaty mess. It's then quickly followed by a rapid drop in temperature that leaves her cold and clammy. Watching her repeated heating and cooling cycles got me wondering about the thermodynamics of a hot flash: how much heat energy gets released in each episode? It shouldn’t be too hard to calculate. We only need three pieces of information: the specific heat capacity for skin, the skin temperature change during a hot flash, and the mass of the flesh getting roasted.

Let’s start with the specific heat capacity for skin. For those of you who may not be familiar with the concept of specific heat, it’s the amount of energy per unit mass needed to raise the temperature of a material by one degree Celsius. A good value for the human body is 3,470 joules per kilogram-degrees Celsius. Don’t worry about those units for now. I’ll relate them to something more familiar later.

Next we need the skin's temperature change during a hot flash, which typically ranges from four to eight degrees Fahrenheit. Kellie’s hot flashes tend to be severe so we’ll use the higher value. And since we’re using the metric system we have to convert to Celsius, giving us a temperature rise of 4.4 degrees. It's like global warming only faster, and there's no chance of melting glaciers unless you send all women over 50 to Antarctica

Lastly, we need the mass of the flesh being heated, a delicate subject when talking about one’s wife. Kellie weighs between 130 and 135 pounds. I’m using the smaller number because I know what’s good for me.  We have to convert to the metric system so that gives us a body weight of about 60 kilograms. Since skin normally accounts for 12 to 15 percent of total body mass, that gives us 7 to 9 kilograms of skin. Gross! Unfortunately, we have to use the higher value because, as even Kellie would admit, baby got back (and some bodacious Ta-Ta’s too), and all that real estate requires a tad more skin.

Now all we have to do is multiply:

Heat = 3470 j/kg-C0 x 9 kg x 4.4 C0 = 137,412 joules

So now you’re probably asking, “What the (expletive) is a joule?” Rather than trying to explain joules, let’s convert it to something more familiar. According to Wikipedia, a stick of dynamite contains about one million joules of energy, and given Kellie’s firing rate, that means that over the last three years her body has exploded the equivalent of 4,809 sticks of dynamite. No wonder she’s been a bit irritable. Luckily, I know how to quench a fire. All she needs is a good hosing. She didn't seem too interested in my analysis. I guess she doesn't understand thermodynamics.
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32 comments:

  1. Is that enough energy to power a flux capacitor? And if not, how many hot flashing women would that take? Er......"hot flash, experiencing women" might be a better way to phrase that.

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  2. I feel Kellie's pain, but I love the humor of this piece.

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  3. Oh, great... something to look forward to.

    You're humor always cracks me up! :)

    BTW... you need to ad your new "Yeah Write" badge! Congrats!

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  4. hehe man when you put it like that! :)

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  5. Women eh! No interest in such a riveting piece of applied mathematics; I'll never understand them.

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  6. Tapping all this female energy could help wean us off of fossil fuels and help our environment.

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  7. It would be the "hosing" that concerned me.

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  8. "I’m using the smaller number because I know what’s good for me." You are a smart man. And by your calculations, you appear smart enough to crack this hot flash code and regulate the menopausal thermostat. Women throughout history would name their children after you. Or maybe it would be their grandchildren.

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  9. so funny and surprisingly informative. :)

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  10. This was really funny. Luckily I read this while not having a hot flash. I can't recall ever thinking anything was funny while having one. If I were having a hot flash, I would comment something like, "Could you please quit talking and open the window. It's too hot in here."

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  11. Never thought a post with the word "joule" in it would make me laugh.

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  12. So hilarious! Your poor wife. :) I am not looking forward to this new phase of my life, but I least I'll be able to brush up on my math.

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  13. I hope your dick falls off...love your little sister xoxo

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  14. Well thanks for clearing that up. Since I hit menopause at around 40, and had one drug induced one during fertility treatments, I think I've exploded 3 times that much. No wonder The Coach drinks so much beer. "Joules" maybe that's why it's called "Beads of Sweat"?

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  15. I can empathize with your poor wife, as I am entering the hot flash zone myself. Entertaining analysis!

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  16. This is hilarious. I think you could probably win a nobel prize for that formula.

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  17. Yeah, after you come up with a formula like that you probably couldn't use the higher number and claim that you aren't good with math. ;)

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  18. I don't think anyone has approached the hotflash from quite this perspective. I'm sure whe appreciates your efforts!

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  19. You crack me up. Giggled throughout. Thank you!

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  20. Really fun post. I especially loved the last few lines! (I'm going to file this info away for when I need it. YOu know, for some sympathy..)

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  21. Hilarious *and* informative! The best kind of post!

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  22. Good LAWD this was funny. And enlightening. And... explosive. Well done, you. :)

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  23. Whew, quite a physics lesson! I'm going to file this away for menopause...

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  24. I love this for many reasons. First, I'm a scientist so I appreciate the calculation. Second, I'm Kellie's age so I have menopause symptoms too, although so far it's mostly not being able to sleep. I'm happy you gave me a way to calculate my dynamite once the dreaded flashes start. You are so funny!

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  25. Oh, Joe... I adore your earnestness in these computations. And your humor!

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  26. Oh, this is brilliant! I'm nominating you for a Nobel Peace Prize (not only for your theories and computations, but for knowing to use your wife's lower weight in your calculations!). Great post!!

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  27. Forgive my ignorance, but when I searched "menopausal hot flashes thermodynamics" (and delighted in finding your calculations), the real question I had was this: if heat exists merely as a byproduct of friction...where's the friction coming from and why? Or am I misunderstanding heat or something else?

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    Replies
    1. Friction is not the only way to produce heat. Heat can also be produced via chemical reactions, nuclear reactions etc... How is heat generated during a hot flash? I can't really say, but it is fun to write about.

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