go pee

[Second Half]

removing silliness

[Del Q]

Here is my current mode...........two large mouth plastic bottles, one for my "hooch" (high octane whiskey), and one for breakfast (carnation instant breakfast/chocolate 2 /day)........hooch goes pretty fast, then use that for my pee bottle

Forgetting the weather or temperature.........at midnight, 4am, whenever, taking care of business in my tent vs getting up and out regardless of weather works great. Back to sleep faster..........then hike all day

This pervades weight discussions.........if the weight of a plastic bottle ever "breaks the bank" I will take on a new hobby..........like chess

[Furlough]

When it first occurs to you go out and pee. If you wait you will stay awake for an hour or so thinking about peeing and THEN get out to pee.

Ain't it the truth? And yet it seems like I always battle it for that additional hour, knowing full well that the bladder always wins the waiting game.

[JAK]

If it is really cold, I will stay in the sack long enough to "plan" my pee expedition. This also gives the adrenaline some time to kick in. In the fall/winter/spring I am only in a bivy/tarp, and not always under a tarp. Sometimes just a big spruce, so I don't have all that far to go. When it's really really cold though, and I'm wearing lots of clothes, and doing weird things with blankets and scarfs and boots and my pack and slowlt freezing to death, it can be a little tricky getting out of the bag and peeing, and getting the last drops out, and getting dressed again, and getting back into the bag and warming up again. Hopefully my new sleeping bag will take care of some of those "issues".

[Sarcasm the elf]

removing silliness

How dare you remove such a thing!!!

[Pedaling Fool]

Now, my background in thermodynamics is from the engineering standpoint. But the simple fact that the surface area of your body does not change means that you are not losing more heat. As a matter of fact, since the water is already at core temp it would theoretically make it take longer for your body to reach ambient if for some reason your body stopped producing heat (greater starting btus, while heat loss remains constant). The withdrawal of blood to the core is to reduce the surface temp of your skin on the extremities, which reduces delta T vs ambient, which reduces heat loss. The surface area of these extremities is what makes them lose heat faster than your core regions.

Having to pee in no way changes the laws of thermodynamics.

Now, if one was extremely dehydrated they might sweat less, thus lose less heat to evaportive cooling. But that will be offset by you drinking water to make up for having peed some of it out. And heating that water will start at ambient temperature, needing to be heated up.

For reference, heating 1 liter of water up to core temp takes about 35 nutritional calories if it stats pretty close to freezing.

I'm no scientist or engineer, but I'm going to have to go with Amanita's analysis. Thermodynamics is a subject that many get wrong based primarily on using "common sense"; here's a pretty good explanation of it using a completely different example, but it shows how a colder object can increase the temp of an already warmer object, just by being placed near that object. Gotta be careful with that common sense approach

It's titled:


Yes, Virginia, Cooler Objects Can Make Warmer Objects Even Warmer Still
July 23rd, 2010 by Roy W. Spencer, Ph. D.

http://www.drroyspencer.com/2010/07/...-warmer-still/

[hikerboy57]

all right, i can accept the explanation that the fluid is already in your system, so wouldnt require extra heat to stay warm. But wouldnt it also hold true that if you eliminate the extra fluid, your body would be more efficient in staying warm?

[Feral Bill]

all right, i can accept the explanation that the fluid is already in your system, so wouldnt require extra heat to stay warm. But wouldnt it also hold true that if you eliminate the extra fluid, your body would be more efficient in staying warm?

No, it would not.

[rocketsocks]

I can't believe this is in the heath and safty thread instead of................

[Sierra Echo]

I went camping on Saturday night and only got up to pee once!!! I was proud of myself!!
My potty break inspired my companion and he went ahead and took care of business as well. coordination is the key!

[beakerman]

the physiology is what changes the picture.there is simply more mass to heat.you are right from a pure thermodynamics point of view.as it gets colder, the body will shut down blood flow to the extremeties to keep the area nearest the heart warm.the more fluid you retain, the more masss to heat, robbing the extremeties of blood flow.rocks dont need to manufacture heat.thats the difference.

The urine is already at body temperature before it gets to the bladder. you are not actively heating it....so how exactly is the body doing anything? Water, which is what 99% of the mass of urine, has a heat capacity of 4.186 joules/g/°C. LEts say you have a truly massive bladder and can hold a full liter of urine and you are the average 5'10" male which would way 180 pounds (82kg). Your urine is approximatley 1.2% of yoru body mass at that point. However that fluid was jsut moments before landing in your blader flowing through your kidney and jsut before that zipping aroudn your body in your blood. All of which was already at or very near yoru body temperature. So what needs heating? Also your bladder is inside your body so its insulated against heat loss jsut like your heart and liver...so what is the body trying to heat or keep warm?

[hikerboy57]

The urine is already at body temperature before it gets to the bladder. you are not actively heating it....so how exactly is the body doing anything? Water, which is what 99% of the mass of urine, has a heat capacity of 4.186 joules/g/°C. LEts say you have a truly massive bladder and can hold a full liter of urine and you are the average 5'10" male which would way 180 pounds (82kg). Your urine is approximatley 1.2% of yoru body mass at that point. However that fluid was jsut moments before landing in your blader flowing through your kidney and jsut before that zipping aroudn your body in your blood. All of which was already at or very near yoru body temperature. So what needs heating? Also your bladder is inside your body so its insulated against heat loss jsut like your heart and liver...so what is the body trying to heat or keep warm?

I understand this but heres what Im having trouble with:lets say you want to heat , say 2L of water to 98.6 deg and maintain that temp,with the air temperature at 25F,i would assume it takes x amount of energy to maintain that temperature. but if you removed say .5L, wouldnt it take less heat/energy to maintain that temp?
I gotta go...

[Feral Bill]

Heat loss depends on A. Surface area,which is more or less constant, B. Temperature difference betwee the surface and surroundings, C. The conductivity of the source and sink (water chills you faster than air), and D. Convective heat loss in fluids (wind chill). None of these are changed by additional mass. If anything, the additional mass of urine is a heat source in a cooling human body. If you go outside to pee, you are literally pissing away heat.

I hope I am being clear.

[hikerboy57]

Heat loss depends on A. Surface area,which is more or less constant, B. Temperature difference betwee the surface and surroundings, C. The conductivity of the source and sink (water chills you faster than air), and D. Convective heat loss in fluids (wind chill). None of these are changed by additional mass. If anything, the additional mass of urine is a heat source in a cooling human body. If you go outside to pee, you are literally pissing away heat.

I hope I am being clear.

Thanks.You're being clear. I think Im the one thats "dense".but you did make it easier for me to understand.i still cant work through the logic the way Id like in my own mind, but thats okay. i accept the conclu.... have to go again, thanks.

[Amanita]

Well think of it this way. If you had a nalgene full of water and an empty nalgene that were both heated to 98 degrees F, and left them out in the cold (sealed up) which would stay warm longer?

The full nalgene has more "heat" in it. The loss of "heat" (be it in joules, kilajoules, british thermal units, or however you want to measure it) is the same for both bottles. They have the same surface area, starting temperature insulation, conduction, convective and radiative properties.

[hikerboy57]

Well think of it this way. If you had a nalgene full of water and an empty nalgene that were both heated to 98 degrees F, and left them out in the cold (sealed up) which would stay warm longer?

The full nalgene has more "heat" in it. The loss of "heat" (be it in joules, kilajoules, british thermal units, or however you want to measure it) is the same for both bottles. They have the same surface area, starting temperature insulation, conduction, convective and radiative properties.

Thank you, thank you. thank you.thats the first time its been explained in a way I understand.
the defense rests.

[leaftye]

Thanks.You're being clear. I think Im the one thats "dense".but you did make it easier for me to understand.i still cant work through the logic the way Id like in my own mind, but thats okay. i accept the conclu.... have to go again, thanks.

When you're thinking of maintaining the temperature of the urine, that implies that you think the energy (heat) is getting lost somehow. Feral Bill is trying to get you to think of ways the energy (heat) can escape because if it can't escape, then it will remain at the same temperature. Forever.

[hikerboy57]

When you're thinking of maintaining the temperature of the urine, that implies that you think the energy (heat) is getting lost somehow. Feral Bill is trying to get you to think of ways the energy (heat) can escape because if it can't escape, then it will remain at the same temperature. Forever.

but that was what was confusing to me, because heat escapes the human body through perspiration and aspiration, unlike the nalgene mentioned above, i didnt believe the body could be treated from the same thermodynamic viewpoint as , say a rock, or a pot of water.amanita gave me the best explanation ye..... uhoh, gotta go.....

[JAK]

I hate walking home in the cold when I need to take a crap. I think having to have a crap, or having a full bladder, might interfere somehow with the bodies ability to generate heat, or conserve heat. Just a hunch.

[Feral Bill]

Well think of it this way. If you had a nalgene full of water and an empty nalgene that were both heated to 98 degrees F, and left them out in the cold (sealed up) which would stay warm longer?

The full nalgene has more "heat" in it. The loss of "heat" (be it in joules, kilajoules, british thermal units, or however you want to measure it) is the same for both bottles. They have the same surface area, starting temperature insulation, conduction, convective and radiative properties.

Excellent explantion! A+ for use of a relevent concrete example.