Rub your hands together quickly. Notice anything? Yup, they should be warming up as you read this. How does this happen? Well any object, no matter how smooth it is, when rubbed against another, produces friction. Friction is the force that opposed motion caused by tiny imperfections on the surfaces running over each other. This month we’re going to explore friction with a metal wire or a coat hanger!
A 6 inch section of a metal wire or a metal coat hanger opened up
Take the piece of wire or coat hanger and bend it back and forth rapidly
Hold your hands close together so you can isolate the bending right in one spot
Don’t do this too much… it might overheat!
From before, friction is the force that opposes motion. When you bend the metal back and forth like this, there are no surfaces rubbing together. But within the metal there are atoms of copper or whatever wire you found still moving past each other. This rapid motion is turned into heat, and metal, being a great conductor of heat and electricity, will pass this heat along itself.
What other things can you do to create friction? Try sliding some blocks across a smooth floor and then across the driveway. Which one of these surfaces produces more friction?
What are some ways that you can reduce the problems that friction might cause? Push a big block over the driveway again, and then try it with a couple of pencils underneath it. This is called “rolling friction” and it is different from “sliding friction.” Oil can also be used to reduce the friction between surfaces. You can push something on your counter and then put a little dab of oil under it after to see how that makes it move. Of course, be careful, as oil can make a mess!
LOOKING FOR MORE science experiments? Find them here!
Steve Davala is a high school chemistry teacher who likes to write. He has written a few Young Adult novels, one called "The Soulkind Awakening." The second is "The Shadow of the Soulkind." He often uses his two children as guinea pigs for these simple science experiments, so you know they’re safe and fun to do.