Brain Teasers
Sink A Needle
How can you sink a needle that is floating in a bowl of water without touching it, dropping anything on it, or shaking the bowl?
Answer
Dish soap! The molecules in dish soap separate the water molecules from each other, and since the surface tension of the water is no longer as great, the needle sinks!This experiment actually works, the trick is using some sewing thread to lower the needle onto the water.
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Comments
Clever!
very cute - i must remember to try this one at home
Aug 31, 2005
this one i can use in a science fair experiment that is easy. thanks for the idea.
Great teaser! I got it, but only because my neice just did this for a science project.
I figure that using a magnet to pull the pin to the bottom of the bowl is the only solution. But that is based on my assumption that I cannot add anything (like soap) to the water because I would cause waves. I think adding soap might violate the "rules" of the game.
I agree with Pascal. I came up with the "correct" answer immediately, but rejected it because it seemed to break the rules as written.
very cool
Never thought of a magnet, good idea.
Good one keep it up
I'm with Pascal and them... Is soap legal in this case?? Maybe we should investigate the effects of Psycho kinetics on the structure of water molecules??? And the magnet, didn't think of that one.
My answer was to put a big magnet underneath the bowl, it should work
I thought you were going to say something like, "well I never said you couldn't push it down using something that isn't yourself... I just said you couldn't drop anything on it."
yeah the rules state that you cant put anything onto the needle so wouldnt pouring soupy water be against the rules???
well i thought of a magnet, but i managed to (of course) make my solution 10 times harder than it could be. lol i thought, "get a magnet of the same force (forgot the right word) and literally use magnitice force to 'push' the needle under. gosh. never thought to put the magnet under the bowl. also didnt think of soap. good one though
I thought I would put the pan of water on the stove heat it until boiling causing the needle to sink. Didn't know about the soap!
Good thinking. Boiling water would also work.
Cool!
Who needs soap? Just suck the water out of the bowl with a straw.
does that qualify as "sinking?" I think not. Anything to break the surface tension works here. There is no rule against making waves, only against touching the needle or shaking the bowl itself.
It's amazing how many correct answers exist to this teaser.
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