Kevin's Blog

It's one of the most memorable applications of thermodyamics in movie history, and it occurs in my favorite movie of all time - A Christmas Story.

Flick: Are you kidding? Stick my tongue to that stupid pole? That's dumb!
Schwartz: That's 'cause you know it'll stick!
Flick: You're full of it!
Schwartz: Oh yeah?
Flick: Yeah!
Schwartz: Well I double-DOG-dare ya!
Ralphie as Adult: [narrating] NOW it was serious. A double-dog-dare. What else was there but a "triple dare ya?" And then, the coup de grace of all dares, the sinister triple-dog-dare.
Schwartz: I TRIPLE-dog-dare ya!
Ralphie as Adult: [narrating] Schwartz created a slight breach of etiquette by skipping the triple dare and going right for the throat!

For those of you with enough sense to never lick a frozen metal pole, you have to still be wondering, could your tongue really stick to that pole?

Several weeks back we talked about burning the roof of your mouth on a piping hot piece of pizza. The theme of that blog was a concept we call thermal conductivity. In honor of winter's official arrival on Sunday morning, it's time to look at the cold side of thermal conductivity.

Heat is energy that moves from warm objects to cold ones. In this case, your warm tongue would be touching a cold metal flagpole. In order for your tongue to stick, the liquid on your tongue would have to be cooled below 32F, and freeze.

But, you know that your tongue is warm and that your body continuously pumps blood to provide heat. So, how on earth can you cool your tongue to a temperature below freezing while all of this heat is being provided?

That's where thermal conductivity comes in! To cool your tongue, the contact point (the flagpole) would have to conduct heat away from your tongue faster than your body can provide the heat. In other words, the pole would have to have a significantly larger thermal conductivity than your tongue.

Mrs. Shields at Harding Elementary School apparently didn't teach thermal conductivity, or Flick must have been absent on the day this topic was covered. After checking with the University of Oklahoma Health Science Center, the best estimate for the thermal conductivity of the saliva on your tongue is approximately 0.7 watts per meter per degree Kelvin.

So what about the flagpole? I drove around Norman, Okla. today and checked out the flagpoles at Lincoln, Monroe, and Madison Elementary Schools (Figuring that all schools across the country named after Presidents had similar flagpoles!). Each was made out of aluminum. The Handbook of Chemistry lists the thermal conductivity of aluminum as 237 watts per meter per degree Kelvin.

Whoa! As your tongue touches the flagpole, the moisture on your tongue is robbed of heat 300 times faster than your body can replace it. The result? Water freezes inside the pores on your tongue and to the surface of the flagpole, and as quick as Flick, you're stuck!

By the way, if you cook on your stovetop you already know that metals like aluminum, copper, etc. have high thermal conductivities! That is why all of your cookware is made out of these materials!

One more piece of advice! Now that you know that you CAN stick your tongue to a frozen flagpole, what on earth do you do if you run across a Flick in your schoolyard?

That's easy. You don't need to call the Fire Department. Simply melt the frozen liquid on the tongue by pouring warm water over the tongue. Do not try to rip your tongue off the pole, or you wilth tawk likth thith for a while!

P.S. Don't shoot your eye out!

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