Braingle: 'Which is Heavier?' Brain Teaser

Which is Heavier?

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

Puzzle ID:	#37426
Fun:	(2.56)
Difficulty:	(1.11)
Category:	Science
Submitted By:	TheSmartest

If you fill a 5 gallon bucket with cold water and another 5 gallon bucket with hot water, which bucket will be heavier?

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Comments

FutureMD Jul 16, 2007	Easy for me becuase the last unit I did in Science involved thermal explansion, but I doubt it will be as easy for every one else. Good teaser!
pokpic Jul 16, 2007	easy but good teaser
RedPython Jul 16, 2007	An Interesting fact. It's always good to read these science teasers. Don't be disheartened by comments that will almost certainly follow telling you it was too easy. With this type of teaser you either know the answer or you don't. Many people will have learnt something new by reading your teaser. As an extra challenge people can ask themselves if the answer would be the same if the cooler water was cooled to a state where it was solid (i.e. 5 gallons of ice) and would the answer be the same if the liquid in question was not water. What would the differences in weight be for hot, cold and frozen liquids other than water (such as oil or ethanol)?
empy Jul 16, 2007	Interesting. I automatically thought of steaming hot, nearly boiling water and thought of evaporation. Molecule spacing never occurred to me.
cooltigerr1 Jul 16, 2007	WAYYYYYY EASY! but i liked it
HarryPutter Jul 16, 2007	too easy!but nice!
coltonr1 Jul 17, 2007	That was pretty good. A little bit hard.
The-stranger0 Jul 17, 2007	kind of obvious you think?
SPUTNIK2 Jul 17, 2007	very interesting, good one!
happyhak Jul 18, 2007	Easy! Got it on my first guess!
spinnercat Jul 20, 2007	I got it on my first guess. (But it was a 50-50 chance so I shouldn't be that happy.)
bobobear Jul 31, 2007	i thoght it was hard
SandUtil Aug 06, 2007	that was easy! Yeah.
jazzmusician46 Aug 07, 2007	Good one! I didn't know...that's because I'm not a science buff (and probably most people on here aren't either), so good teaser. I learnt something new today. Thanks.
billhardy Sep 14, 2007	the cold watermolecules aren't denser. They are packed c;oser tp gether, and there are more of them om the bucket, that there are in the hot water bucket.
TheSmartest Sep 14, 2007	Billhardy: I do believe that denser means "packed closely together" or "closer together" ..... DUH.
IQ_master Oct 14, 2007	thats kinda easy (:
browns2397 Oct 14, 2007	for me,that is a simple question The answer is Cold \ make harder questions!
AndrewWalker Nov 05, 2007	That's only true if the water is no colder than 4 deegrees C. Ice is 9% less dense than liquid water.
ElectronJohn Nov 28, 2007	I agree with Andrew. You need to know the temp of the water to answer the question correctly. Ice floats in water because it is less dense then the liquid water around it.
ElectronJohn Nov 28, 2007	Actually this is very much like my "cold and warm gasoline" teaser I submitted a few years back. This is probably not considered a duplicate though since you are talking about water and weight and mine is dealing with gasoline and volume.
moody12345 Nov 28, 2007	I wasn't quite sure what it was....... then I read the answer. That was a very interesting fact!
CatsAreCute Jan 15, 2008	Fun! But TOO EASY!!!
rockstar1234567 Jan 26, 2008	i love science
friesaregood Apr 17, 2008	Wow, that's interesting!
tangled_brain May 04, 2008	you're right, "Smartest," but your answer is not. "Denser" does mean packed more closely together, but you used the word wrong. The Molecules are not denser, they are all the same H2O-the 5-gallon sample is denser. They both have the same volume, but the cold sample actually has more molecules. Also, when measuring the volume, the meniscus would be minutely different- the hotter sample's meniscus would be flatter, making you even put fewer molecules in your container. Of course, this is all on a ridiculously small scale. BTW, DUH.
Wa11E Sep 20, 2008	Are we have heavy water!