an important question

[Boirunner]

if i were lying in the bathtub, fully submerged in water, and i peed.

would the water level rise?

[Sgt Doom]

No. You see, it's a safety feature built into all baths when it's about to overflow, urine and other unwholesome bodily secretions get sent via portal onto a random banker's head as punishment for causing the economic crisis.

[Jazcash]

No because Archimede's principal would prove that the mass of the piss weighing into the water would rise the water level anyway. No matter where the piss is, if it's still under the water level, the water level will stay the same.

If you were to piss into the bath (preferably while someone isn't in it), then the water level would rise.

[Regret]

No matter where the piss is, if it's still under the water level, the water level will stay the same.

Wrong.

A closed empty bottle in a bathtub would lift the water level as much as a closed full bottle in a bathtub. Now emptying the full bottle into the bathtub then closing it and putting it into the bathtub would result in a higher water level than in previous two experiments.

(assuming that the overflow holes are not reached and that the empty/full bottles wont float)

[Kloot]

A closed empty bottle in a bathtub would lift the water level as much as a closed full bottle in a bathtub.

No it wouldn't.

An empty bottle displaces X liters of water.

A full bottle displaces Y liters of water.

A full bottle has more mass than an empty one, so lies deeper in the water, so pushes a greater volume of it out of the way, so Y > X.

edit: bah, missed the non-floating assumption.

[Pxtl]

I don't think my bladder is full of air when it's empty like a bottle. My penis doesn't take in air after I pee. Bladders collapse.

[Regret]

edit: bah, missed the non-floating assumption.

http://www.youtube.com/watch?v=rX7wtNOkuHo

Bladders collapse.

Irrelevantly small collapse on the outside of your body compared to the amount of piss.

[lurker]

edit: bah, missed the non-floating assumption.

http://www.youtube.com/watch?v=rX7wtNOkuHo

It's still a ridiculous assumption. The ideal bottle has negligible volume and negligible weight.

Bladders collapse.

Irrelevantly small collapse on the outside of your body compared to the amount of piss.

Do you have any reason to say it's that small?

[Jazcash]

If you put the full bottle under the water then opened the cap, the water level would stay the same. If you put the empty bottle under the water than opened the cap, the water level would lower.

Ofc emptying the full bottle into the bath tub would raise the water level because you're adding the bottle's contents straight into it.

[lurker]

It doesn't matter because you're holding it under the water with a large force. You're doing a smaller version of putting down a piston into the water to build pressure and possibly change the level by feet.

[Regret]

It's still a ridiculous assumption. The ideal bottle has negligible volume and negligible weight.

It is not ridiculous as your bladder does not float in the water.

Do you have any reason to say it's that small?

Yes, next time you pee, take a good look on how much the volume of your body changes.

[lurker]

If you shoved it full of air and sealed it, of course it would float. If you want a comparison to a bladder use a plastic baggie. If you want a good bottle test that actually makes sense, take your bottle of water under the surface and squeeze it out. No water level change.

I can do that, sure, but for a test I can do right now, repeatedly, is breathing out about as much as that, and my body doesn't shift very much.

[Regret]

If you shoved it full of air and sealed it, of course it would float. If you want a comparison to a bladder use a plastic baggie. If you want a good bottle test that actually makes sense, take your bottle of water under the surface and squeeze it out. No water level change.

Bladder is part of your body, feel free to separate it.

I can do that, sure, but for a test I can do right now, repeatedly, is breathing out about as much as that, and my body doesn't shift very much.

Lungs != bladder.

[Jazcash]

Do you have any reason to say it's that small?

Yes, next time you pee, take a good look down.

[Strategia]

You body mass stays the same, the pee mass leaves your body and enters the water. Don't forget that it is mass, not size, that matters in Archimedes' Law. Your body size may only decrease a tiny bit, the total mass stays the same. Hence no change. It's a zero-sum game.

[lurker]

I'm wrong to compare two organs that are largely sacks of uncompressed fluid? What's special about the bladder that would make your body stay the same size as it empties, and what are you suggesting fills up the space no longer taken by that urine?

[Regret]

You body mass stays the same, the pee mass leaves your body and enters the water. Don't forget that it is mass, not size, that matters in Archimedes' Law. Your body size may only decrease a tiny bit, the total mass stays the same. Hence no change. It's a zero-sum game.

In this particular scenario involving bladder, you fail at both anatomy and physics.

I'm wrong to compare two organs that are largely sacks of uncompressed fluid? What's special about the bladder that would make your body stay the same size as it empties, and what are you suggesting fills up the space taken by the bladder?

http://medicalimages.allrefer.com/large ... biopsy.jpg

http://www.ama-assn.org/ama1/pub/upload ... storso.gif

Do you see the difference in positions those organs have? Bladder collapsing has little effect on the body volume as opposed to lungs collapsing.

[Strategia]

In this particular scenario involving bladder, you fail at both anatomy and physics.

The mass of the urine leaves the body, the bladder contracts, there is nothing to replace that urine. And the total amount of mass in the water stays the same - the mass of your body decreases, but the mass of the water increases with an equal amount.

[CarRepairer]

You body mass stays the same, the pee mass leaves your body and enters the water. Don't forget that it is mass, not size, that matters in Archimedes' Law. Your body size may only decrease a tiny bit, the total mass stays the same. Hence no change. It's a zero-sum game.

No, it's volume, not mass.

[lurker]

And in the scenario you describe no organs shift downwards, the skin doesn't shift in at all, and the space vacated by the urine is now devoted to?