How come your tongue sticks to a cold pole or pipe? is a question that has come up several times for my newspaper column Ask Your Science Teacher. This silly and stupid deed was made famous in the A Christmas Story movie. Recall that nine-year old 'Ralphie' Parker wants a Red Ryder BB gun for Christmas if only he can convince Santa Claus, his mother, and his father that he won't shoot his eye out with it.
A danger for little kids was the tongue on the pump handle or in the movie scene, a flag pole. There was always some dummy who would do it, especially on a double dare. A kid just can’t chicken out on a triple dare!
Of course, every Scheckel boy tried it on the pump handle or uprights on the windmill on the Seneca, Wisconsin farm sometime in the late 1940s and early 1950s. We all lost a bit of tongue skin on those episodes.
So, scientifically, what is going on? The moisture on your skin or tongue can freeze and bond you to any metallic object. This fusing of skin to metal will happen when you touch a metal surface. Metals are excellent conductors of heat.
There are three methods of heat transfer; conduction, convection, and radiation. Conduction is a molecule to molecule process. If you put an iron rod into a fire, the end you are holding will soon be very warm. The heat, which is the movement or jiggling of molecules, was transferred from one molecule to the next. This process is like lining a bunch of people up right next to each other and then each person nudges the person next to him or her. The jostling travels down the line of people. The molecules on the heated end of the rod started jumping and bouncing around. This shaking of molecules travels along the rod and pretty soon you're holding the jumping molecules, which is heat.
Convection is heat transfer by currents. Most people heat their house by convection currents. Gas or oil furnaces heat air which travels up the ducts. Radiation is solar, light, or electromagnetic waves. If you let the sun hit your face, you can feel the warmth. This is radiation.
If you touch your kitchen countertop, you would say it is feels fairly warm. But, if you touch the kitchen faucet, you say it feels cool. Actually, the countertop and the faucet are the same temperature. The faucet feels cool because it conducts heat away from your hand. Your hand loses heat, so you say the faucet is cool. Ever wonder why toilet seats are made of plastic or wood and not made of metal? By the way, bed pans in hospitals are made of stainless steel which happens to be a poor conductor of heat.
When your wet hand or tongue touches very cold metal, heat is conducted away from the skin quickly and the moisture on your skin or tongue freezes, bonding your skin to the cold metal. Haven't we all, as youngsters, been told not to go out on a cold winter day and put your tongue on the pump handle? Of course, most of us probably gave it try.
When I was growing up on a farm in Crawford County, our mother gave us some good advice. She said to never stick your tongue on the hub cap of a passing farm pick-up!!