Braingle: 'Cork in a Glass' Brain Teaser

Cork in a Glass

Science brain teasers require understanding of the physical or biological world and the laws that govern it.

Puzzle ID:	#5737
Fun:	(3.01)
Difficulty:	(2.29)
Category:	Science
Submitted By:	Bobbrt

If a cork is put into a glass of water, the cork will almost always drift to the side of the glass. There is one simple way, however, to get the cork to float in the center of the glass (the horizontal center, not the vertical). What is it? Water, the glass, and the cork are all that is required.

Answer

The reason that a cork drifts to the side of a glass is that it floats to the highest point. Since water "clings" to the glass, the highest point is around the edge of the water. To get the cork to float in the middle of the glass, all you have to do is fill the glass as much as possible. The water will form a convex shape above the glass, with the highest point at its center. This is where the cork will settle.
Hide

What Next?

See another brain teaser just like this one...

Or, just get a random brain teaser

If you become a registered user you can vote on this brain teaser, keep track of
which ones you have seen, and even make your own.

Comments

heavenlycupcake Jul 27, 2002	Thats cool. I never thought of that.
zangel3000 Jul 30, 2002	I'm not a big sci fan, but I actually liked that!
Yogi Jul 30, 2002	Bravo!
mrbump999 Aug 07, 2002	By swirling the glass you could create a slight whirl pool, which would also centralise the cork. I think the other answer is better - so you should say 'without touching the glass....'
(user deleted) Aug 08, 2002	i thought maybe.. it wud hv been that hold it with ur hand.. cos u didnt mention 'without using ur hands' so u shud hv mentioned that. good teaser anyway...
agozzardbes Aug 09, 2002	adding detergent to break the surface tension of the water and stop the drift to the side, but the cork would not be fixed by any means to the centre of the glass
bill2k2 Aug 10, 2002	I've got another solution: freeze the water, then place the cork in the middle of the glass.
bmotts Aug 15, 2002	IF there's one bad cork teaser, I haven't heard it!
dsquared Aug 19, 2002	I was with you bill2k2... still the real in-depth scientific answer is pretty cool. I really like these science ones - not because I ever get them, just because I learnt heaps o' freaky stuff. dsquared scientist
A_n_d_y Aug 21, 2002	Why is there water in the glass if a bottle of wine has just been uncorked?
pemalova Aug 21, 2002	the convex shape...if I'm correct, it's called a meniscus. I know that's what it is if it's concave, but I'm no Bill Nye, so don't take my word for it. Anyway, I surprisingly got it!
doggyxp Aug 22, 2002	You can do that with a penny. Take a water dropper and drop the water on bit by bit. A dome will form over the penny.
Vandrian Oct 27, 2002	What happens if you create a water current with a temperature change? Will it create a fluid motion on the side of the glass, and a vortex in the center of the glass? I like the answer above a/b freezing it.
vexicor Nov 17, 2002	If there is not a lot of water in the bottle you could turn it sideways andd put the cork in then it would float in the middle. Wouldn't it? Well, good teaser anyway.
Princess_Neopia Dec 30, 2002	Great teaser.
glyn1wood Dec 31, 2002	what if you used a circular fall of water so the cork floated inside this. the cork would bounce back into the centre of the glass and never escape. i like it though
jellybean May 07, 2003	what if you put the cork in first then poured the water in slowly so the water is only about half way up the cork and so the bottom of the cork is still slightly touching the bottom.. then it will stay in the middle!!! but i like ur scientific answer better
Jessicag Aug 21, 2003	...or you could have a glass that is exactly the same with as the cork, then It wouldn't have an oppurtunity to move one side or the other.
(user deleted) Aug 21, 2003	You also didn't say it was "tap" water. Carbonated water would force it towards the middle as well. At least soda does this (I didn't have any carbonated water on hand). I love these interactive puzzles (and so does my 4yo). Shaking up the can a bit will encourage the fizz btw, so lay out a big towel first (learned this the hard way LOL).
gingimo711 Aug 21, 2003	i was thinking fill the glass just a little tiny bit and have the string on the cork not long enough to reach the sides, making it float in the middle.
camsha Aug 25, 2003	If you have the patience, you could hold the cork in the center for about an hour. When you let go, the cork would stay put right in the center. Oh yeah, you should also try this while you are outside in sub freezing weather. Cork in an ice cube!
melybug Aug 22, 2004	thats cool!!! where that one did you learn
marigold Feb 12, 2005	I'm not a big scince wiz but... I'll have to ask my science teacher that one.
drussel3 Jun 02, 2005	How about you empty the water out, and roll the cork around to the middle.
arabiannights Feb 19, 2007	Great! Really cooool!
Smudge Feb 19, 2007	The solution was quite obvious. Once you think about the reason the cork goes to the edge (because of the viscosity of water), you can almost immediately figure out that to achieve a centered cork, you'd need to alter that. That said, my immediate thoughts were that you could get a glass (because the size of the glass isn't specified) that was the same size as the cork, and hence the cork would be in the middle once you squash it into the glass.
choptlivva Feb 19, 2007	Great teaser! I like these science ones coz they encourage creative thinking!
craniac Feb 19, 2007	But the point of science is that only empirically proven solutions are admissible. Speculation may be a good way to come up with hypothetical answers, but only actual experiment can prove if an answer is correct.
bradon182001 Feb 19, 2007	Very interesting teaser. Will have to try it for myself. Thanks for the science lesson.
puttumup Feb 19, 2007	very nice .one.. to the rest of you clowns who said freeze the water or other diffirent solutions .did you kill some braincells ?..cmon there is only answer..to the teaser..
marschie Feb 19, 2007	I thought the answer would be that you blow down, vertically, on the glass with the cork and water in it. I'll try it the next time I have a cork to put in a glass of water. I thought this because of what happens when you put a working fan under a balloon. The balloon will, I think, stay within the flow of air. (I guess I'll have to try that, too, sometime.)
kitty728 Feb 19, 2007	you could stick 2 wooden skewers to the bottom of the cork (horizontally) then place it in the glass and add the water. you didnt say we couldnt cheat.....lol
FatHead Feb 19, 2007	Now if that isn't the textbook definition of cool. Well, kinda.
tpkarth Feb 19, 2007	Cool.. easy, as I have heard it before of course:-)
masquerademe235 Feb 19, 2007	good teaser- never thought of that. I thought maybe swirling the water so that the cork would settle in the center of a whirlpool kinda thing.
scallio Feb 19, 2007	I too thought swirling it was the answer... oops! Great teaser!
speedqueenkmw Feb 19, 2007	I didn't know any of that information....so now I do. thanks
saleprice Feb 19, 2007	schmedley, there is absolutely no need whatso ever to be so disgusting.... there are those of us who find that kind of gutter language offensive and besides it shows your lack of intelligence and vocabulary...........keep it off this site
auntiesis Feb 19, 2007	I thought profanity was forbidden on this site. Please remember the kids who use Braingle for heaven's sake. That said, I thought it was a great teaser.
jcann Feb 19, 2007	Would someone please explain to me how to use the "This is offensive" thing? I clicked it once before when someone had used language that I was offended by, but nothing happened. Does it have to be reported by a certain number of people first, so that one person can not just make that judgement call?(That seems fair to me.) If so, let's do what we can to get rid of the foul language.
Pizzazz2u Feb 19, 2007	A fantastic Science teaser. Being just the one answer, teasers dealing with science have always intriqued me. Keep up the terrific work! All of us need to have a few teasers to work our minds with.
jabdr Feb 19, 2007	Good answer Make my idea of covering only the bottom of the glass with water and sitting the (assumed, heavier) cork in the middle look pretty silly. Good job
senther7 Feb 19, 2007	Nice teaser, but i think u could also put little water in it so the cork is WAY above the water, then just balence it in the bowl (i am joking) Good science anyway
vlerma Feb 19, 2007	After I found out nothing else was involved unfortunately I was stumped. Nice teaser.
breathesunshine Feb 19, 2007	Good one, makes you think!
notsosmart111 Feb 21, 2007	Very clever!
Qrystal Feb 26, 2007	Ahhhh, that's a good teaser. My guess was that it would have something to do with saturating the cork with water, but didn't know if that would actually work. I also thought about altering the surface tension, but then we couldn't add anything (like detergent, as someone above said).
TallTimber Feb 19, 2010	Somehow I knew this. Thanks fo posting it.
patiencewithaP Feb 19, 2010	Good one! Even though I was wrong!
dalfamnest Feb 22, 2010	Very clever, and a good thought-provoker. Thanks!
Babe Feb 19, 2013	Why would I want to do this in the first place? What is the point of doing it? Sorry!!!
cutebug Feb 19, 2013	Babe, nobody ask you to do it. It was a teaser question,and I knew the answer from high school science classes many moons ago. Nice teaser.
gaylewolf Feb 19, 2013	Babe, you're not related to Doehead are you? You sound a little, tiny bit negative today. ok Sorry! These are puzzles and some thing to think about - not necessarily suggestions of "things to do" ! Have a great day - you, too, DH!