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Science        < Previous        Next >


You 'Get It' About Hot, Warm and Cold.

Oh, Yeah?!?


Today's Snack: If we're going to be concentrating on contrasting temperatures, there are no two ways about it. We HAVE to splurge and have hot-fudge sundaes today. If you can serve low-fat frozen yogurt or ice milk, that would save on the fat and calories of ice cream. But as long as you keep your sundae to one or two dips, it won't be so bad. You also can find sugar-free and/or low-fat fudge sauce, believe it or not, in the diet aisle. Put a glass jar of it in the microwave and heat for one minute on high. Be SURE to take the metal lid off first - duh! Just kidding. Stir after a minute, and if it's still cool or just warm, put it in for another minute on high. Stir again. When it's pretty darned hot, glob a nice big glob on top of your froyo or ice milk. The best part of all is watching the fudge sl-o-o-o-owly dribble down the scoop. Oh, yeah!






Three cups

Tap water

Ice cubes

Quick access to a microwave oven

Blindfold (if more than one person is present)



You know about our friends, the molecules. They're the tiny little conglomerations of even tinier little atoms. Well, there are tons and tons and TONS of molecules right in your chubby little fingers. You can't even COUNT them, there are so many! Bet you didn't know you had soooo many little bitty parts of yourself.


Aha! I just saw one MOVE! AAAIIIIEEE!!!!


Just kidding. Ahem. Just a little science humor there.


Anyway, the point is, yes, molecules really DO move. They're moving all the time. Obviously, they're so eentsy weentsy, you can't even see them, much less see them move - even if you squint really, really hard.


There's that nerdy science humor again. Sorry.


ANYway . . . there are molecules in the tissues of your fingertips that can vibrate, or move, thousands of times per second. Imagine that! Try wiggling your finger for one second. Did you maybe move it five or six times? Well, big whoop - compared to a molecule!


But the thing is, the warmer these molecules get, the faster they vibrate. That's how we can come up with the temperature of an object: we measure the average motion, or "kinetic" (meaning movement) energy, of the object's molecules.


You also have to keep in mind that these measurements of heat are all relative. You can actually "trick" your senses based on the environment in which you are measuring, based on what's going on with your molecules.


Let's demonstrate this:


If you're by yourself, do this activity by yourself, but repeat it later with somebody else and blindfold them to take them through the activity and see the big surprise.


ANYway . . . fill the three cups with tap water, only put one in the microwave and get it quite warm, though not too hot to the touch. Try 30 seconds on high, but if that's too hot to stick your finger in the water comfortably, let it cool off 'til you can. Make the second one at room temperature of water. And fill the third one with cold water, with a couple of ice cubes added for good measure. You should end up with warm-almost-hot, room temp, and ice-cold cups of water.


Put them in front of you in that order - warm, regular, cold.


Now put your left index finger (your "pointer" finger) in the warm water and your right index finger in the cold water. Count to 20, slowly.


As soon as you're done, quickly dip both fingers into the room temperature water in the middle of the three cups.


Notice what your fingers are "telling" you:


Your left index finger will feel like it is submerged in cool water, while your right index finger will "think" it's in warm water.


Yet they're in the same darned container with the same darned temperature!


When you do this to someone blindfolded, ask them at the end if their two fingers are in two different containers, or the same one. Most times, they'll INSIST they're in two different containers! You will laugh like crazy, and they will be mad, frustrated and protesting. Enjoy!


Those fingers are confused! They belong in a Digital Loony Bin. (Get it? Fingers are, after all, "digits"? Sigh. Sorry, again.)


Anyway . . .


How come this happens? Well, it goes back to our crazy, dancing molecules. When the left finger was in the hot-warm water, it absorbed some of the heat, which made those skin molecules vibrate like crazy. Then when you put it into the regular-temperature water, some of that heat was transferred out of the finger, into the water. The finger which a second ago felt pretty warm suddenly feels cool because the vibrational energy of its molecules has slowed down quickly.


Similarly, when the other finger was plunged in the ice-cold water for 20 seconds, molecular action was slowed down because of the cold. Then when that cold finger was shifted into the regular-temperature water, it quickly absorbed some of the heat-energy from it, and felt warmer as a result.


Hot-warm-cold molecules in your fingers. Cool! Do you give that a . . . THUMBS UP?


By Susan Darst Williams Science 03 2008




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