You are an astronaut, it is a few hours before you are scheduled to launch for an intergalactic space mission, and you're sitting on the shore of the Atlantic Ocean near Cape Canaveral, savoring the view one last time. This mission is especially trying; because of the relativistic speed of your spaceship, Earth will be one billion years into the future upon your return.
Depressed beyond words, you decide, in one of your weaker moments, to pee into the Atlantic Ocean.
Flash forward: 1 billion years .
You return to Earth, expecting a hero's welcome, but instead you find that all of humanity has vanished. Instead, the Earth is run by a peaceful clan of telekinetic dolphins who made off with the lion's share of Bitcoins that were abandoned by the last humans as they uploaded their souls to the singularity server. In a disillusioned haze, you bend down and fill your astronaut survival cup with refreshing lake water, hoping for some clarity. After drinking the glass, you realize that this far into the future, all the Earth's water has been thoroughly well mixed since the time you took off on your mission.
Approximately how many molecules of your billion year old urine did you just consume?
Assumptions and details
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But it has been 1 million years so It would decompose into its constituents thus 0 should be the answer. Inorganic things like plastic take such long time, not organic
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The problem tells you to assume your urine is pure water, so decomposition wouldn't be taken into account.
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The water molecules can be combined into minerals. H2O in minerals can come out as liquid water. Furthermore, H2O in the atmosphere can be broken down by UV and H2 lost to space.
*1 billion years
it says he drinks lake water, not water from the atlantic, so isn't your answer wrong?
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It also says all the water on the earth has been thoroughly mixed which is why he's taken into account all sea water on earth
yh its obvious in 1 bln years everything will be mixed up properly
It's based on the water cycle—the oceans will all have evaporated and precipitated somewhere else on the planet over that timescale!
The person must be having a very large bladder... :)
The answer should be 0
Do u guys have any idea that molecules can be dissociated after 1 yr, now u talk about a billion year.This question is data inadequate Natural phenomenon can be taken as negligible?? I know how big Na (avagadro number), still molecules can decompose.
Your answer tells you how many molecules from 1 liter would exist in an average liter of water thoroughly mixed with your estimate of the free water on earth in 1 billion years(which should also have been a given since it is merely a guess), but the problem states a sip was taken, not a liter. Therefore, your solution is wrong.
How do I know the capacity of his mouth?
how large is his survival cup?
is urine's Mr= 18 .... i think urine containts CO(NH2)2, NaCl, bilirubin, biliverdin etc. so it shouldn't be 18 ....
@josh silverman how can you think of such a question?
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@Satvik Golechha No idea. I would sooner touch the moon than try to figure out where this story came from.
You did not provide the information on the remaining volume of seawater on earth after 1billion years! And he just sipped the water, he did not drink all the water from the cup.
But he only takes one sip instead of 1 liter
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Good point. I've changed it so that he drinks the full cup.
0, because homeopathy is useless.
I think that the dolphins would kill him so could not drink any water so 0
Moreover urine is mostly just water, molecules of which would be indistinguishable from rest of the ocean water. So only a small fraction of molecules from that urine would be identifiable.
He did not drink 1 liter of water, he drank 1 cup for god's sake... The question was, how much urin did he drink, not how much urin is there in 1 l of current ocean water....
The answer should be 0. I understand the point of fermi estimates... but realistically, all the urine would be filtered out of the water eventually.
you wouldn't be alive after 1 billion years :P
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You will, due to time dilation, your body would not develop too much.
Ratio of urine volume to volume of all water (assuming it has all been made into liquid form) on earth= 1L/(1.26x10^21 L) Source: howstuffworks
Number of molecules in a cup of water: 8.36 x 10^24 molecules of water Source: username another_someone
The sources were not tested for reliability at all.
(Number of H2O molecules in a cup of water) * (Ratio of urine volume to volume of all water) = 6634.920634(repeating) This is closest in orders of magnitude to 25,000.
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Weight of urine=1000L (1 gm/L)=1000 gms. Molar wt of urine(pure water)=18gms/mole. No of moles=1000/18 moles. No of molecules=1000/18 * Na=1000/18 6 10^23 molecules. volume of earth's sea water=1.33 10^21 L So, no of molecules per liter=1000/18 6 (10^23)/4 3 10^-21 molecules/liter. =1000/4*100=25000 molecules approx.