Hot & Cold

We all know when something feels hot or cold, but did you ever think about what causes it to feel that way? You probably know that everything is made up of molecules, which tiny bits of matter. When something feels hot, it means that the molecules are moving very fast. So, how do the molecules move when something is cold? That's right - they're slow.

Now, you might think that you could never see how fast molecules move. After all, they're really tiny, and your eyes aren't that good! But you can do an experiment that will let you see the effect of their motion. Here's what you need:

2 drinking glasses of the same size and shape
Food coloring
Hot water (from the faucet is OK, but make sure you don't get scalded)
Cold water (also from the faucet)

Fill one glass with hot water. Fill the other glass to the same level with cold water. Add 3 drops of food coloring to each glass. Watch for a few minutes. What do you see? Can you explain your results based on the different speeds of the molecules in hot and cold water?