Frozen Tongue

Well, you're stuck. I won't ask how you got here in the first place, but I can help you out. Before I can tell you how to free yourself, let's think about why the pole is trying so hard to hold onto you. The basic principle behind this is the second law of thermodynamics. The formal definition of this law is that the entropy of an isolated system always increases. It isn't actually as complicated as it sounds. Entropy can be thought of as a measure of disorder. If you clean up your room, over time, it will eventually become messy again. In other words, it goes back to being disordered. The same thing happens when we look at thermodynamics. If you have a hot object and a cold object placed together, they start ordered, kind of like how the books in your room are kept neatly on a shelf. However, as time goes on, the hot and cold will mix to become some middle temperature (Figure 1). This is analogous to how you eventually move the books around, making them disordered.

In order to satisfy increasing entropy (Second Law of Thermodynamics), bringing a hot and a cold object near each other will result in heat going from the hot object to the cold object. This is demonstrated in the top part of Figure 2. The heat transfer continues until they reach a state called thermal equilibrium in which no more heat transfer occurs between the two objects. This is demonstrated in the bottom part of Figure 2. The scenario actually relates very closely to our situation at hand. Your tongue acts as the warm object and the pole acts as the cold object. As soon as you put your tongue on the pole, heat starts to transfer from your tongue into the pole. The transfer can be simplified as both your tongue warming up the pole and the pole cooling down your tongue.

Now that we understand why the pole cools down a tongue, we can begin to see why the tongue gets stuck to the pole. Saliva coating your tongue is approximated to consist of 99% water. As heat energy is taken from your tongue into the pole, the temperature of the saliva is decreased. As this temperature gets close to 0 ℃, the heat energy goes into changing the state of the saliva from liquid to solid, meaning the saliva begins to freeze. Now that the saliva surrounding your tongue is frozen and attached to the pole, you're stuck! It's so easy to get your tongue stuck to a pole because it has a high thermal conductivity. This means that it can transfer heat energy in shorter amounts of time, which is why your tongue gets stuck so quickly, without giving you the opportunity to remove it. Now, to remove your tongue from the pole, all you need to do is pour some warm water on it (Figure 3). This can transfer heat energy into the frozen saliva, melting it and allowing you to pull off your tongue!