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Falling Water
Thu Feb 06, 2003
Listen in RealAudio 
Last month we posited a brainstorm about water. Does an object fall through water faster at
25 or 75 degrees Fahrenheit. Hi, I'm Bryan Yeaton for The Weather Notebook. The answers that
we got show that our listeners know their physics. Here's Ellen Cosgrove from Albuquerque,
New Mexico.
EC: I believe that the marble would fall faster through 75 degree water because the electrons
would be further apart, the water molecules would be further apart the warmer it gets.
OK, that's true but water has some other interesting properties as eight-year-old Carrie Ann
told us from Tennessee.
CA: The answer is 75 degrees Fahrenheit because at 25 degrees Fahrenheit it would be
frozen.
Ah, there's the key. Twenty-five degree water is ice. But some objects do get through ice as
John Wax of Buffalo told us.
JW: I have tried several times to get various objects to transcend that mystical barrier of
25 degree Fahrenheit water. Rocks, marbles, and nails, and eventually with bullets because
none of the other objects would travel fast enough.
So, it was a bit of a trick question, but even that's not the whole story. Pat McDonald of
Omaha, Nebraska.
PMcD: At 25 degrees water is in a super-cooled state and is getting ready to freeze or is
looking for an excuse to do so.
So, water can still be liquid at below, so-called freezing. Jim Joseph of Buffalo explains
one place where it happens.
JJ: I guess near the bottom of the ocean the pressure is so great that the water doesn't have
the room to expand or crystallize and turn into ice.
The Weather Notebook is supported by Subaru of America and The National Science Foundation.
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