/sci/ - Science & Math

[Anonymous No.6037906]

A glassfull of water from the bottom of the ocean would weigh more than a glassful filled from the top because of the pressure wouldn't it?

[Anonymous No.6037927]

maybe?
is it being measured at the bottom of the ocean?

[Anonymous No.6037929]

>>6037906
Dude... wat?

>The weight of an object is taken to be the force on the object due to gravity.

Or are you implying it'll weigh more because the density is greater at the bottom because of the pressure? If this is the case I'm guessing the difference would be negligible and could be ignored.

[Anonymous No.6037946]

If you brought the cup up, it would rise or spill out after less density. If you took a cup down it would appear to bee less volume

[Anonymous No.6037958]

>>6037929
Oh, so there's not really that much compressed to notice a difference?

shieet

[Anonymous No.6037961]

>>6037929
The increase in density with depth isn't something trivial you can ignore. I wish I could find it but there was this video that really showed the effect: A pod containing research equipment sprung a pinhole leak a few kilometers down and filled with water over the course of days. Not much pressure managed to escape back out the hole as it was being lifted up. As the hatch was being opened it exploded outward like a fire hydrant for a fraction of a second. It could have taken someone's head off.

[Anonymous No.6037962]

>>6037958
not really.

liquids aren't very compressible

[Anonymous No.6037964]

Maybe the pressure at the bottom would make the glass smaller.

[Anonymous No.6037965]

>>6037961
Or.. you know, the water didn't actually compress that much and instead the pod was stretched outward dude to the immense pressure inside only to spring back to it's original size/shape when given relief.

I'm a little curious though as what the difference in density would be now.

Also, your picture doesn't mention anything about temperature, which has a much larger effect on density than anything else.

[Anonymous No.6037966]

>>6037961
of course, by your own graph, you can see that after the first 1000 meters, increasing depth has essentially no effect on water density.

[Anonymous No.6037971]

>>6037906
from wiki:

The low compressibility of water means that even in the deep oceans at 4 km depth, where pressures are 40 MPa, there is only a 1.8% decrease in volume.

[Anonymous No.6037975]

>>6037965
deep ocean temperatures are a narrow range of slightly sub-zero celsius across the globe..

[Anonymous No.6037984]

>>6037965
Although this idea seems doubtful at first, there may have been empty spaces in the walls of the pod that would have allowed the inside to compress outwards thereby increasing the internal volume.

[Anonymous No.6037992]

>>6037975
And as you can see by the picture density changes very little deep down. As this guy said:
>>6037966

The majority of the change in density is near the surface where there's also the largest change in temperature so I'm wondering if whoever made this picture included it or not.
>>6037906
TL;DR OP:

For all intents and purposes the answer is No. The glass of water would not "weigh" more at the bottom due to pressure. This is generally true for all solids and liquids anywhere on earth, that is, the same solids/liquids will weigh the same everywhere on earth.

Unless you're being specific you can ignore all other variables: pressure, temperature, salinity, elevation (depth), tidal forces, etc.

[Anonymous No.6038028]

>control f yes
>0 results
Everyone shut the fuck up.
Ofcourse it would weigh more. Also it would expand because of atoms or molecules get compressed together.

[Anonymous No.6039855]

A glassful of water from the bottom of the ocean would weigh less than a glassful from the top because the gravitational attraction of the water above would cancel some of the gravity from below, wouldn't it?

[Anonymous No.6039862]

>>6039855
Well, if you weighed the samples right when/where you sampled them, yes. It would also weigh more if you used a larger glass or weighed it on the sun.

[Anonymous No.6039890]

>>6039855

You are correct that gravity would be less, but the difference would be even smaller than the 1.8% difference caused by increased density.

[None !!BJiYgff8zf2 No.6039968]

>>6039855
>>6039862
>>6039890

By that logic, gravity would be stronger on top of a mountain because you have the whole mass of the mountain plus the mass of the earth pulling on you, whereas at the bottom of a mountain the mountain is pulling you upwards cancelling the rest of the earth's gravity.

[Anonymous No.6039974]

>>6039968
>can't into high school gravity.

[None !!BJiYgff8zf2 No.6039977]

>>6039974
>can't think of a serious response
>better accuse him of being a highschooler!

[Anonymous No.6040012]

>>6039977
Your logic is shit, the mass above you in fact does cancel the gravity and the deeper you go the less gravity there is.
These guys are just also wrong:
>>6039862
>>6039890
>>6039968
Because they don't take into account that the density isn't constant. The gravity rises for a bit because crust is light and you'll get closer to the heavy core before starting to fall linearly.

[Anonymous No.6040030]

>>6037961
Facinating

[Anonymous No.6040075]

depends if it is open or not, if it is, more water molecules will be inside the glass.

[Anonymous No.6040084]

>>6037961
shouldn't the density of water be 1 at the top?
you know, since the gram is defined by a cubic centimeter of water and all?

[Anonymous No.6040089]

>>6039968
>By that logic, gravity would be stronger on top of a mountain because you have the whole mass of the mountain plus the mass of the earth pulling on you
yes

[Anonymous No.6040097]

>>6040084
>you know, since the gram is defined by a cubic centimeter of water and all?

Well first of all, no it isn't anymore. But more importantly, that would be a gram of FRESH water anyway. Salt water has a higher density.

[Anonymous No.6040150]

>>6040097
>Salt water has a higher density
I feel like a retard for not thinking of that.

but the gram is still defined by a cubic meter of water at 4 degrees though

[Anonymous No.6040154]

>>6040150
>but the gram is still defined by a cubic meter of water at 4 degrees though

Nope, not since 1889. A gram is defined as 1/1000th the mass of a certain cylinder of platinum-iridium alloy that's sitting in a basement in Paris.

[Anonymous No.6040185]

>>6040154
well, originally the gram was defined by one cm3 of water. that cylinder is based on that gram. (on paper a cm3 of water is exactly one gram)
also there are a few copies of that cylinder scattered across a few countries and after a few dozen years of storage none of them are actually the exact same weight so using water as the definition is still more accurate

[Anonymous No.6040213]

>>6040185
Actually a cubic centimetre of water is 0.998203 grams. Didn't even have to google that, I work in a field that requires me to know that.

[Anonymous No.6040217]

>>6040213
what field is that if I may ask?

[Anonymous No.6040221]

>>6040213
>gives density of water to 6 decimal places

>doesn't specify temperature or pressure

[Anonymous No.6040222]

>>6040185
>well, originally the gram was defined by one cm3 of water.

Yes, but it has not been in over a century.

>that cylinder is based on that gram

The cylinder is a physical object. It's based on itself. But yes, it is very close to the mass of 1 liter of water, which is the old (and now inaccurate) definition of the kilogram.

>>6040185
>also there are a few copies of that cylinder scattered across a few countries and after a few dozen years of storage none of them are actually the exact same weight so using water as the definition is still more accurate

No, it is NOT "more accurate." It is wrong. A cubic centimeter of water does NOT weigh 1 gram. If a copy of the cylinder is a different mass, then it's not 1 kg either. The definition is the mass of the original, not the copies.

[Anonymous No.6040225]

>>6040217
... I work in a laboratory in a cider factory. We use density meters to 6sf to estimate sweetness. They measure at rtp.

It's probably so lowly that you fuckers will totally ridicule it, but I get a great salary and new challenges every day. I also have to taste test cider daily.

I recently took control of our waste water treatment plant. They're more complicated than you might think.

[Anonymous No.6040226]

>>6040213
you are aware of the fact that density changes with temperature, right?
are you sure that water isn't just 0.998203 g/cm3 at the room temperature where you work?

[Anonymous No.6040229]

>>6040226
We use density meters which heat or cool the liquid to standard rtp.

We're thick but not stupid.

[Anonymous No.6040233]

>>6040222
So, if I got my hands on the original, and cut a slice off, everything would become more massive?

The original is treated as the standard. But the original's mass is changing. But the unit is held to be constant.

So the standard is not really "the definition". It's just a standard we use so we have a standard, though we know it's imperfect, and we're working to replace it with a standard that can be recreated independently from the specification and won't change over time.

[Anonymous No.6040238]

>>6040229
as I said earlier in the thread, 1cm3 of water at 4° is exactly one gram. and in case you don't know the density of water will decrease with higher temperature

[Anonymous No.6040242]

>>6040238
Missed the bit about 4 degrees. My bad.

[Anonymous No.6040241]

>>6040238
>as I said earlier in the thread, 1cm3 of water at 4° is exactly one gram.

No it isn't.

[Anonymous No.6040244]

>>6040225
Sounds like an awesome job to me.

/sci/'s full of 14-year-olds who all think they're going to be Nobel-Prize-winning research scientists because they got top marks in junior high school science class.

[Anonymous No.6040245]

>>6040238
Who the fuck measures stuff at 4 degrees?

[Anonymous No.6040247]

>>6040241
>No it isn't.
ok, when you put it like that I guess I can't refute you.
seriously though, just google it you dense fuck
>>6040242
no biggie m8

[Anonymous No.6040246]

>>6040233
>So, if I got my hands on the original, and cut a slice off, everything would become more massive?

If you did that, it would be without a formal definition until it is formally redefined, likely in terms of fundamental constants (as it likely will be within 2 years anyway).

>we're working to replace it with a standard that can be recreated independently from the specification and won't change over time

Yes we are. But we haven't yet.

[Anonymous No.6040250]

>>6040247
>seriously though, just google it you >1 g/cc fuck

[Anonymous No.6040251]

water cant get any more or less dense. So that isn't true.

[Anonymous No.6040252]

What many are failing to account for is the concentration of salt and particulates in the water. The solubility of such compounds are an important factor in determining the density of the solution at the different temperatures and pressures. Depending where you are at the bottom of the ocean, you can actually find lakes of denser liquids that produce a mirror like meniscus.

[Anonymous No.6040258]

>>6040245
it's not like people have to cool water down to 4° and put it on a scale each time the want to weigh something. the kg has to be defined with something

[Anonymous No.6040263]

>>6040247

>Modern measurements of Vienna Standard Mean Ocean Water, which is pure distilled water with an isotopic composition representative of the average of the world’s oceans, show it has a density of 0.999975 ±0.000001 kg/L at its point of maximum density (3.984 °C) under one standard atmosphere (760 torr) of pressure

What's that? You realize you're wrong? Finally!

[Anonymous No.6040266]

>>6040251
right, because nothing can ever be compressed...
is this nigga serious?

[Anonymous No.6040273]

>>6040263
fuck

[Anonymous No.6040276]

>>6040266

Strangely enough, water is more dense in its liquid form than its solid form.

[Anonymous No.6040295]

>>6040276
that's actually because of the way the molecules arrange when they become a solid

[Anonymous No.6041277]

>>6039890
A glass full of less dense water near the surface of the ocean would weigh more then the a glass full near the bottom. The weight of the glass is the same but the buoyant force is equal to the weight of the volume of water displaced by the glass. More dense near the bottom, the water would weigh more and buoy up the glass more.