# 32 foot limit **URL:** \ **Category:** Factual Questions\ **Created:** [July 3, 2003, 11:42am UTC](https://boards.straightdope.com/t/32-foot-limit/185992 "2003-07-03T11:42:47Z")\ **Posts on this page:** 19\ **Page:** 2
**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:** [July 3, 2003, 3:36pm UTC](https://boards.straightdope.com/t/32-foot-limit/185992/21 "2003-07-03T15:36:52Z")
MInd you, the gravity on Jupiter (if the term ‘on’ means anything at all in this context) is probably pretty high too, so maybe it would cancel out. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [July 3, 2003, 11:21pm UTC](https://boards.straightdope.com/t/32-foot-limit/185992/22 "2003-07-03T23:21:17Z")
> [@](#): > > MInd you, the gravity on Jupiter (if the term ‘on’ means anything at all in this context) is probably pretty high too, so maybe it would cancel out. No, the gravity is what’s causing the high pressure to begin with. For the gravity to “cancel out” the pressure would be equivalent to a scale which balances on the Earth not balancing on Jupiter. You would have to do more work to pump water to a given height on Jupiter (in proportion to the surface gravity), but the upper limit of how high you could pump it would be greater (in proportion to the atmospheric pressure). ---
**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:** [July 4, 2003, 12:00am UTC](https://boards.straightdope.com/t/32-foot-limit/185992/23 "2003-07-04T00:00:48Z")
> [@](#): > > \*Originally posted by Chronos \* > **No, the gravity is what’s causing the high pressure to begin with. For the gravity to “cancel out” the pressure would be equivalent to a scale which balances on the Earth not balancing on Jupiter.** I’m sure you’re right (I don’t know a lot aboutthese sorts of things), but wouldn’t the actual mix of gases also affect the pressure? ---
**Author:** ![Desmostylus](https://avatars.discourse-cdn.com/v4/letter/d/c57346/32.png) [@Desmostylus](https://boards.straightdope.com/u/Desmostylus)\ **Post date:** [July 4, 2003, 12:27am UTC](https://boards.straightdope.com/t/32-foot-limit/185992/24 "2003-07-04T00:27:39Z")
Bit complicated. The gravity does cancel out the pressure to some extent. Venus has a surface pressure of 90 atm, and a surface gravity of 0.91 g. The column of water (assuming we could keep it cool enough) would be 32’ x 90 / 0.91 = 3,200’. Jupiter has a surface pressure of 100 atm, and a surface gravity of 2.6 g. The column of water (assuming we could keep it warm enough) would be 32’ x 100 / 2.6 = 1,200’. ---
**Author:** ![kanicbird](https://avatars.discourse-cdn.com/v4/letter/k/5f8ce5/32.png) [@kanicbird](https://boards.straightdope.com/u/kanicbird)\ **Post date:** [July 4, 2003, 12:40am UTC](https://boards.straightdope.com/t/32-foot-limit/185992/25 "2003-07-04T00:40:15Z")
Just to go on the other side, I have a well w/ a submersible pump that pumps the water up almost 500 ft into a presurized cisteen. ---
**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:** [July 4, 2003, 12:51am UTC](https://boards.straightdope.com/t/32-foot-limit/185992/26 "2003-07-04T00:51:39Z")
This is why the very first steam engines (which were devised for the purpose of pumping water out of coal mines) didn’t try to ‘suck’ the water out; the power was transmitted to the pump at the bottom of the shaft by a long rod. ---
**Author:** ![Princhester](https://avatars.discourse-cdn.com/v4/letter/p/3e96dc/32.png) [@Princhester](https://boards.straightdope.com/u/Princhester)\ **Post date:** [July 4, 2003, 4:15am UTC](https://boards.straightdope.com/t/32-foot-limit/185992/27 "2003-07-04T04:15:28Z")
> [@](#): > > \*Originally posted by r\_k \* > \*\*Oh, and if you want a bit of maths to prove it, I’ll have a go at working it out from first principles: > > If a column of air 1-inch square extending all the way to the “top” of the atmosphere could be weighed, this column of air would weigh approximately 14.7 pounds at sea level. Thus, atmospheric pressure at sea level is approximately 14.7 psi. ([Cite](http://www.tpub.com/fluid/ch1d.htm)) > > The density of water is 1 g cm[sup]-3[/sup], which is (1 x 2.54[sup]3[/sup] = 16.4 g per cubic inch or 16.4/(28.35 x 16) = 0.0361 pounds per cubic inch. (Because there are 2.54 cm in an inch, 28.35 grams in an ounce and 16 ounces in a pound.) > > So imagine a column of water with cross-section 1 square inch. How high does it have to be for the mass of the water to equal 14.7 lb? > > Answer = 14.7/0.0361 = 407 inches, or 33.9ft. > > I assume that the small discrepancy is because you can never achieve a true vacuum with a pump in the real world, so there will always be a bit of pressure keeping the water from reaching its full potential height. \*\* Total aside: **r\_k** a fine post, but for frig’s sake why not just bleedin’ well use metric all the way through? Sheesh. Talk about making things hard for yourself! 🙂 ---
**Author:** ![Evil\_Captor](https://avatars.discourse-cdn.com/v4/letter/e/f17d59/32.png) [@Evil\_Captor](https://boards.straightdope.com/u/Evil_Captor)\ **Post date:** [July 4, 2003, 1:48pm UTC](https://boards.straightdope.com/t/32-foot-limit/185992/28 "2003-07-04T13:48:30Z")
So, has anybody ever figured out how trees get water up beyond 32 feet without an active pumping mechanism? ---
**Author:** ![Desmostylus](https://avatars.discourse-cdn.com/v4/letter/d/c57346/32.png) [@Desmostylus](https://boards.straightdope.com/u/Desmostylus)\ **Post date:** [July 4, 2003, 2:00pm UTC](https://boards.straightdope.com/t/32-foot-limit/185992/29 "2003-07-04T14:00:07Z")
Look here for the tree stuff: [http://www.hcs.ohio-state.edu/hcs300/pstrans.htm](http://www.hcs.ohio-state.edu/hcs300/pstrans.htm) Basically, the answer is “capillary action”. ---
**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:** [July 4, 2003, 2:01pm UTC](https://boards.straightdope.com/t/32-foot-limit/185992/30 "2003-07-04T14:01:44Z")
The vessels inside of trees are very narrow; effects like capilliary action and surface tension (which can be safely ignored in larger experiments) suddenly become very significant factors. (Is capilliary action _caused_ by surface tension?) ---
**Author:** ![Desmostylus](https://avatars.discourse-cdn.com/v4/letter/d/c57346/32.png) [@Desmostylus](https://boards.straightdope.com/u/Desmostylus)\ **Post date:** [July 4, 2003, 2:08pm UTC](https://boards.straightdope.com/t/32-foot-limit/185992/31 "2003-07-04T14:08:29Z")
> [@](#): > > \*Originally posted by Mangetout \* > \*\*(Is capilliary action _caused_ by surface tension?) \*\* It’s caused by two factors. Surface tension and adhesion to the walls of the vessel. Adhesion drags molecules at the walls upward. Surface tension drags other molecules up with them. ---
**Author:** ![Colophon](https://avatars.discourse-cdn.com/v4/letter/c/f05b48/32.png) [@Colophon](https://boards.straightdope.com/u/Colophon)\ **Post date:** [July 4, 2003, 2:57pm UTC](https://boards.straightdope.com/t/32-foot-limit/185992/32 "2003-07-04T14:57:32Z")
> [@](#): > > Total aside: r\_k a fine post, but for frig’s sake why not just bleedin’ well use metric all the way through? Hmm, it would have been easier, wouldn’t it? I guess I was trying to make allowances for those Yankees and their quaint ol’ imperial units. Also the original question used feet, and my cite for atmospheric pressure used psi, so I’d have had to do one lot of conversion calculations either way. Hell, I was just pleased I came out with the right answer, give or take a little 🙂 ---
**Author:** ![MonkeyMensch](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@MonkeyMensch](https://boards.straightdope.com/u/MonkeyMensch)\ **Post date:** [July 4, 2003, 7:52pm UTC](https://boards.straightdope.com/t/32-foot-limit/185992/33 "2003-07-04T19:52:56Z")
And there ain’t no pilots here. It’s 29.92 inches of mercury for standard atmosphere. 992 to anyone adjusting their Higg’s windows. ---
**Author:** ![MonkeyMensch](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@MonkeyMensch](https://boards.straightdope.com/u/MonkeyMensch)\ **Post date:** [July 4, 2003, 7:54pm UTC](https://boards.straightdope.com/t/32-foot-limit/185992/34 "2003-07-04T19:54:53Z")
Sorry. Kollsman window. My bad ---
**Author:** ![Anga](https://avatars.discourse-cdn.com/v4/letter/a/57b2e6/32.png) [@Anga](https://boards.straightdope.com/u/Anga)\ **Post date:** [August 7, 2003, 5:47am UTC](https://boards.straightdope.com/t/32-foot-limit/185992/35 "2003-08-07T05:47:59Z")
Sorry to take so long to reply to all of you. A most excellent response time on your part in any case. I now understand that: 1. Water can only be sucked up 32 feet (give or take a few sixteenth inches) 2. Water can be pumped up many feet (I wonder if there is a limit?) 3. People still call southerners ‘Yanks’! #$%!@! I ain’t no damned yankee!!! Thanks again all -Anga ---
**Author:** ![scr4](https://avatars.discourse-cdn.com/v4/letter/s/59ef9b/32.png) [@scr4](https://boards.straightdope.com/u/scr4)\ **Post date:** [August 7, 2003, 6:19am UTC](https://boards.straightdope.com/t/32-foot-limit/185992/36 "2003-08-07T06:19:57Z")
> [@](#): > > \*Originally posted by Anga \* > **2) Water can be pumped up many feet (I wonder if there is a limit?)** There is no theoretical limit. The practical limit is determined by the strength of the pipe and the power of the pump. A good bicycle pump can manage 150 psi, so assuming it works just as well with water (I don’t see why not) it can pump water 320 ft up. ---
**Author:** ![dnooman](https://avatars.discourse-cdn.com/v4/letter/d/839c29/32.png) [@dnooman](https://boards.straightdope.com/u/dnooman)\ **Post date:** [August 7, 2003, 8:27am UTC](https://boards.straightdope.com/t/32-foot-limit/185992/37 "2003-08-07T08:27:04Z")
Slight hijack. Would one be able to have the hose in a simple siphoning system rise above 32 feet? Say, with 1 full baby pool and one empty, one raised higher than the other, and a 75’ hose between them. ---
**Author:** ![Desmostylus](https://avatars.discourse-cdn.com/v4/letter/d/c57346/32.png) [@Desmostylus](https://boards.straightdope.com/u/Desmostylus)\ **Post date:** [August 7, 2003, 9:39am UTC](https://boards.straightdope.com/t/32-foot-limit/185992/38 "2003-08-07T09:39:11Z")
> [@](#): > > \*Originally posted by dnooman \* > **Would one be able to have the hose in a simple siphoning system rise above 32 feet?** No. It’s exactly the same situation. You’re trying to suck water up. ---
**Author:** ![Colophon](https://avatars.discourse-cdn.com/v4/letter/c/f05b48/32.png) [@Colophon](https://boards.straightdope.com/u/Colophon)\ **Post date:** [August 7, 2003, 11:24am UTC](https://boards.straightdope.com/t/32-foot-limit/185992/39 "2003-08-07T11:24:36Z")
**Anga** , no offence was intended with the Y word. Us Limeys use it indiscriminately to refer to those from across the pond, whether they’re from Nashville or New York. Go figure (as I believe you say over there 🙂 ). [Previous page](https://boards.straightdope.com/t/32-foot-limit/185992.md?page=1)