# Objects that don't float in water, sink to the bottom ... **URL:** \ **Category:** Factual Questions\ **Created:** [March 29, 2004, 8:49pm UTC](https://boards.straightdope.com/t/objects-that-dont-float-in-water-sink-to-the-bottom/237159 "2004-03-29T20:49:17Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![SettingSun](https://avatars.discourse-cdn.com/v4/letter/s/7cd45c/32.png) [@SettingSun](https://boards.straightdope.com/u/SettingSun)\ **Post date:** [March 29, 2004, 11:57pm UTC](https://boards.straightdope.com/t/objects-that-dont-float-in-water-sink-to-the-bottom/237159/21 "2004-03-29T23:57:09Z")
> [@Mangetout](#): > > What will happen if the object precisely of the same overall density as water - i.e. the water it displaces when fully immersed weighs exactly the same as the object? I tend to agree with you. However, has it ever been demonstrated? Does the minute compressibility of water have an effect? The “law” has been around for a long, long, time, why hasn’t been challenged? ---
**Author:** ![The\_Hamster\_King](https://avatars.discourse-cdn.com/v4/letter/t/8edcca/32.png) [@The\_Hamster\_King](https://boards.straightdope.com/u/The_Hamster_King)\ **Post date:** [March 29, 2004, 11:58pm UTC](https://boards.straightdope.com/t/objects-that-dont-float-in-water-sink-to-the-bottom/237159/22 "2004-03-29T23:58:58Z")
On this page you can see a photograph of a basketball suspended in a state of perfect neutral bouyancy: [http://www.eyestorm.com/feature/ED2n\_article.asp?article\_id=13&artist\_id=15](http://www.eyestorm.com/feature/ED2n_article.asp?article_id=13&artist_id=15) It’s from a 1985 installation art piece by Jeff Koons. It’s hard to achieve, yes … kind of like balancing a pencil on its tip … but not impossible. ---
**Author:** ![Cervaise](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cervaise/32/16693_2.png) [@Cervaise](https://boards.straightdope.com/u/Cervaise)\ **Post date:** [March 30, 2004, 12:03am UTC](https://boards.straightdope.com/t/objects-that-dont-float-in-water-sink-to-the-bottom/237159/23 "2004-03-30T00:03:13Z")
> [@Mangetout](#): > > What will happen if the object precisely of the same overall density as water - i.e. the water it displaces when fully immersed weighs exactly the same as the object? Dude! Don’t cross the streams! ---
**Author:** ![galt](https://avatars.discourse-cdn.com/v4/letter/g/35a633/32.png) [@galt](https://boards.straightdope.com/u/galt)\ **Post date:** [March 30, 2004, 12:04am UTC](https://boards.straightdope.com/t/objects-that-dont-float-in-water-sink-to-the-bottom/237159/24 "2004-03-30T00:04:43Z")
Aren’t liquid water molecules neutrally buoyant in water? ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [March 30, 2004, 12:05am UTC](https://boards.straightdope.com/t/objects-that-dont-float-in-water-sink-to-the-bottom/237159/25 "2004-03-30T00:05:09Z")
> [@SettingSun](#): > > I tend to agree with you. However, has it ever been demonstrated? Does the minute compressibility of water have an effect? The “law” has been around for a long, long, time, why hasn’t been challenged? If the object was exactly as compressible as water, it wouldn’t matter at all. If the object was less compressible than water, it would tend to stabilise it. If the object was more compressible than water, it would be hard to make it stay in one place. ---
**Author:** ![SettingSun](https://avatars.discourse-cdn.com/v4/letter/s/7cd45c/32.png) [@SettingSun](https://boards.straightdope.com/u/SettingSun)\ **Post date:** [March 30, 2004, 12:05am UTC](https://boards.straightdope.com/t/objects-that-dont-float-in-water-sink-to-the-bottom/237159/26 "2004-03-30T00:05:38Z")
> [@Pochacco](#): > > On this page you can see a photograph of a basketball suspended in a state of perfect neutral bouyancy: > > [http://www.eyestorm.com/feature/ED2n\_article.asp?article\_id=13&artist\_id=15](http://www.eyestorm.com/feature/ED2n_article.asp?article_id=13&artist_id=15) > > It’s from a 1985 installation art piece by Jeff Koons. It’s hard to achieve, yes … kind of like balancing a pencil on its tip … but not impossible. Umm … This **stillborn allusion** was further nuanced in Koons’ ‘Equilibrium Tanks’, a series of one, two and three basketballs adrift in aquariums perched on **state-of-the-art vibration control pads**. 😛 ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [March 30, 2004, 12:07am UTC](https://boards.straightdope.com/t/objects-that-dont-float-in-water-sink-to-the-bottom/237159/27 "2004-03-30T00:07:12Z")
> [@galt](#): > > Aren’t liquid water molecules neutrally buoyant in water? This was to be my next question, dammit! ---
**Author:** ![The\_Hamster\_King](https://avatars.discourse-cdn.com/v4/letter/t/8edcca/32.png) [@The\_Hamster\_King](https://boards.straightdope.com/u/The_Hamster_King)\ **Post date:** [March 30, 2004, 12:17am UTC](https://boards.straightdope.com/t/objects-that-dont-float-in-water-sink-to-the-bottom/237159/28 "2004-03-30T00:17:58Z")
> [@SettingSun](#): > > Umm … This **stillborn allusion** was further nuanced in Koons’ ‘Equilibrium Tanks’, a series of one, two and three basketballs adrift in aquariums perched on **state-of-the-art vibration control pads**. 😛 Your point being? The fact the tanks are mounted on vibration control pads shows exactly how delicate a balancing act neutral bouyancy is. But the basketball really is just floating there … there’s nothing holding it in place. Neutral bouyancy is certainly possible. You just have to keep the liquid still enough. ---
**Author:** ![sturmhauke](https://avatars.discourse-cdn.com/v4/letter/s/e47c2d/32.png) [@sturmhauke](https://boards.straightdope.com/u/sturmhauke)\ **Post date:** [March 30, 2004, 12:20am UTC](https://boards.straightdope.com/t/objects-that-dont-float-in-water-sink-to-the-bottom/237159/29 "2004-03-30T00:20:20Z")
> [@](#): > > Archimede’s principle states that the weight of a floating object is equal to the weight of the water displaced by the object. The bit about neutral buoyancy being impossible is not actually part of the law. While it may be difficult to acheive true neutral buoyancy, it is theoretically possible. ---
**Author:** ![SettingSun](https://avatars.discourse-cdn.com/v4/letter/s/7cd45c/32.png) [@SettingSun](https://boards.straightdope.com/u/SettingSun)\ **Post date:** [March 30, 2004, 12:21am UTC](https://boards.straightdope.com/t/objects-that-dont-float-in-water-sink-to-the-bottom/237159/30 "2004-03-30T00:21:59Z")
> [@Pochacco](#): > > Your point being? The fact the tanks are mounted on vibration control pads shows exactly how delicate a balancing act neutral bouyancy is. But the basketball really is just floating there … there’s nothing holding it in place. > > Neutral bouyancy is certainly possible. You just have to keep the liquid still enough. So, the vibration pads aren’t imparting energy to the BB’s? ---
**Author:** ![Gorsnak](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gorsnak/32/7587_2.png) [@Gorsnak](https://boards.straightdope.com/u/Gorsnak)\ **Post date:** [March 30, 2004, 12:22am UTC](https://boards.straightdope.com/t/objects-that-dont-float-in-water-sink-to-the-bottom/237159/31 "2004-03-30T00:22:59Z")
> [@SettingSun](#): > > I tend to agree with you. However, has it ever been demonstrated? Does the minute compressibility of water have an effect? The “law” has been around for a long, long, time, why hasn’t been challenged? In fact, the minute compressibility has known effects, which have been understood for centuries. Just for example, the [Galileo thermometer](http://www.howstuffworks.com/question663.htm). ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [March 30, 2004, 12:29am UTC](https://boards.straightdope.com/t/objects-that-dont-float-in-water-sink-to-the-bottom/237159/32 "2004-03-30T00:29:08Z")
> [@SettingSun](#): > > So, the vibration pads aren’t imparting energy to the BB’s? No, they are to stop the pounding feet of the plebs from disturbing the balance. ---
**Author:** ![The\_Hamster\_King](https://avatars.discourse-cdn.com/v4/letter/t/8edcca/32.png) [@The\_Hamster\_King](https://boards.straightdope.com/u/The_Hamster_King)\ **Post date:** [March 30, 2004, 12:30am UTC](https://boards.straightdope.com/t/objects-that-dont-float-in-water-sink-to-the-bottom/237159/33 "2004-03-30T00:30:50Z")
> [@SettingSun](#): > > So, the vibration pads aren’t imparting energy to the BB’s? No. They’re just isolating the system from the natural vibrations caused by people’s footsteps and vehicular traffic. I’m sure Koons could have dispensed with the vibration control table if he’d located the tank deep in an isolated mineshaft. That would kind of defeated its utility as an installation art piece though … . ---
**Author:** ![SettingSun](https://avatars.discourse-cdn.com/v4/letter/s/7cd45c/32.png) [@SettingSun](https://boards.straightdope.com/u/SettingSun)\ **Post date:** [March 30, 2004, 12:31am UTC](https://boards.straightdope.com/t/objects-that-dont-float-in-water-sink-to-the-bottom/237159/34 "2004-03-30T00:31:54Z")
> [@Mangetout](#): > > No, they are to stop the pounding feet of the plebs from disturbing the balance. Ah, … 🙂 ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [March 30, 2004, 12:32am UTC](https://boards.straightdope.com/t/objects-that-dont-float-in-water-sink-to-the-bottom/237159/35 "2004-03-30T00:32:10Z")
> [@Gorsnak](#): > > In fact, the minute compressibility has known effects, which have been understood for centuries. Just for example, the [Galileo thermometer](http://www.howstuffworks.com/question663.htm). [nitpick]The water in a Galileo thermometer is changing in density due to thermal expansion and contraction, not compression; there’s an air gap at the top. (although of course the system is sealed, so the water probably _is_ compressing a tiny amount as it warms, but not nearly as much as the air in the top - the compression must be negligible for this apparatus) ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [March 30, 2004, 12:33am UTC](https://boards.straightdope.com/t/objects-that-dont-float-in-water-sink-to-the-bottom/237159/36 "2004-03-30T00:33:56Z")
> [@Pochacco](#): > > No. They’re just isolating the system from the natural vibrations caused by people’s footsteps and vehicular traffic. I’m sure Koons could have dispensed with the vibration control table if he’d located the tank deep in an isolated mineshaft. That would kind of defeated its utility as an installation art piece though … . I dunno; art being what it is, he could probably have installed it at the bottom of a mineshaft and left the public to ponder the deep existential meaning of its absence. ---
**Author:** ![sinjin](https://avatars.discourse-cdn.com/v4/letter/s/ebca7d/32.png) [@sinjin](https://boards.straightdope.com/u/sinjin)\ **Post date:** [March 30, 2004, 12:51am UTC](https://boards.straightdope.com/t/objects-that-dont-float-in-water-sink-to-the-bottom/237159/37 "2004-03-30T00:51:31Z")
The forces acting on a submerged object are the weight of the object (acting down) and the bouyancy force of the fluid (acting up). The bouyancy force of the fluid acting up is equal to the volume of the fluid displaced by the submerged object times the specific weight of the fluid. When these two forces are in equilibrium neutral bouyancy is achieved the object neither sinks nor rises. See any Intro to Fluid Mechanics book for a diagram and a simple derivation involving simple calculus. Saying that neutral bouyancy is impossible is akin to saying that objects can’t float partially submerged. It’s the same principle and the same equation is used to determine how much of the object is actually submerged and how much bobs above the surface. ---
**Author:** ![CoatOfArms](https://avatars.discourse-cdn.com/v4/letter/c/c68b51/32.png) [@CoatOfArms](https://boards.straightdope.com/u/CoatOfArms)\ **Post date:** [March 30, 2004, 12:56am UTC](https://boards.straightdope.com/t/objects-that-dont-float-in-water-sink-to-the-bottom/237159/38 "2004-03-30T00:56:17Z")
> [@Mangetout](#): > > [nitpick]The water in a Galileo thermometer is changing in density due to thermal expansion and contraction, not compression; there’s an air gap at the top. Whew, thought it might be the thermal expansion and compression of the globules in the Galileo thermometer versus compression due to water depth. ---
**Author:** ![sinjin](https://avatars.discourse-cdn.com/v4/letter/s/ebca7d/32.png) [@sinjin](https://boards.straightdope.com/u/sinjin)\ **Post date:** [March 30, 2004, 12:56am UTC](https://boards.straightdope.com/t/objects-that-dont-float-in-water-sink-to-the-bottom/237159/39 "2004-03-30T00:56:43Z")
And I just went to the Koons site above and have no idea why he had to consult with so many physicists:… “he worked with over 50 physicists, including Nobel Prize-winning Richard Feynman, to produce the ‘Equilibrium Tanks’”… Maybe they all went out for beers or something. This is not rocket science people. ---
**Author:** ![SettingSun](https://avatars.discourse-cdn.com/v4/letter/s/7cd45c/32.png) [@SettingSun](https://boards.straightdope.com/u/SettingSun)\ **Post date:** [March 30, 2004, 1:10am UTC](https://boards.straightdope.com/t/objects-that-dont-float-in-water-sink-to-the-bottom/237159/40 "2004-03-30T01:10:53Z")
> [@PictsiePat](#): > > Saying that neutral bouyancy is impossible is akin to saying that objects can’t float partially submerged. You’ll have answer the OP if you can name one object that “floats” submerged? Please cite? [Previous page](https://boards.straightdope.com/t/objects-that-dont-float-in-water-sink-to-the-bottom/237159.md?page=1) [Next page](https://boards.straightdope.com/t/objects-that-dont-float-in-water-sink-to-the-bottom/237159.md?page=3)