February Trivia Game

[stinkfish]

Why does hot water freeze faster than cold?

[StL FinFan]

it doesn't, unless you are talking about impure water, in which case heating it to a boil will raise the freezing temperature because when water has additives the freezing temperature is lowered, so the boiled water would freeze faster

[NADS]

Name the movie Humpty and 2Pac were in.

[Tenshot13]

2 dudes 1 shot?

[YoFuggedaboutit]

Name the movie Humpty and 2Pac were in.

Nothing But Trouble.  Starred Chevy Chase, Demi Moore, Dan Akroyd and John Candy.

[Phishfan]

I thought the rules were only the person who answered the last question was suppose to post a new one. We are getting questions out of the woodwork now. Let's stick to the plan to avoid confusion or quit the thread.

[Brian Fein]

I wanna know if STL is right on the boiled water thing.

I think if you turned your tap to hot and filled a cup, and then turned it to cold and filled a cup, then put both cups in the freezer, there's no way the hot cup would freeze first.

[Phishfan]

I wanna know if STL is right on the boiled water thing.

I think if you turned your tap to hot and filled a cup, and then turned it to cold and filled a cup, then put both cups in the freezer, there's no way the hot cup would freeze first.

It doesn't. It is a wive's tale that got around.

[StL FinFan]

You know how much chemisty and physics you have to take to go to vet school?  A lot.

[Dave Gray]

It doesn't. It is a wive's tale that got around.

Yeah....it's bullshit.

Hot water takes energy to turn to cold water, then takes energy to turn cold water into ice.  (transferring to a new state of matter)

Cold water gets to skip that first step.

[Brian Fein]

Actually, hot water requires the removal of energy to turn it to cold water.

I had heard earlier this week on TV that cold water boils faster than hot water, which I also thought was BS.

[fyo]

HOT AND COLD WATER

I'm a physicist. This is my area. I know what I'm talking about.

It's true. Under *certain* conditions, hot water will freeze before cold water. It's called the Mpemba Effect.

Yeah, it's unintuitive and sounds like utter bull. The real world is pretty complicated sometimes and "water" isn't just defined by it's temperature. When you take a container of hot water and start cooling it (e.g. sticking it in the freezer), the temperature is no longer going to be uniform. There might be convection as well. The amount of gas ("air": nitrogen, carbon dioxide etc) dissolved in the water is going to be different in the warm water compared to the cold water. All sorts of crap.

Bottom line: It's true. It's proven. It's NOT well understood.

You'd think something as seemingly simple as freezing water would be perfectly understood, but the number of variables is astounding.

It's a bad trivia question, though: It's poorly understood and the right answer to the question is "it depends" (and it's not entirely clear on what).

If you want to read more about the Mpemba Effect, there are numerous sources:

Recent articles:
 American Journal of Physics: http://adsabs.harvard.edu/abs/2009AmJPh..77...27K
 American Physical Society: http://adsabs.harvard.edu/abs/2008APS..MAR.K1133T
 Physica A: http://adsabs.harvard.edu/abs/2008PhyA..387..757E

Other links:
Physics World: http://physicsworld.com/cws/article/print/24493
The Straight Dope: http://www.straightdope.com/columns/read/422/which-freezes-faster-hot-water-or-cold-water
Wikipedia: http://en.wikipedia.org/wiki/Mpemba_effect
Various universities:
http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/freezhot.html
http://www.lsbu.ac.uk/water/explan.html#mpemba
http://math.ucr.edu/home/baez/physics/General/hot_water.html#Experiments

[StL FinFan]

Uh..so ask another question then.

[fyo]

Uh..so ask another question then.

Tommy's up, right?

[StL FinFan]

Tommy's up, right?

If no one answered fyo's question correctly, then he should ask another one.