Dr. Mothbold’s automatic polka-dotting machine can paint polka dots on anything – shirts, socks, pancakes, and even pretzels!
Best of all, the polka-dotter is a perpetual motion machine. Perpetual motion is motion, or movement, that goes on forever.
All the parts of the polka-dotter create forces that make the other parts work. As each part gets a push or pull, it gives a push or pull to another part. So, says Dr. Mothbold proudly, this machine will never stop! Is the doctor right?
No. Although pushes and pulls will keep the machine going for a while, other things will make it slow down. Friction is one of these things. The rubbing of wheels against the belt, the brushes rubbing as they paint and the bumping of the brushes on the paint lever will slow down the machine. Finally, the automatic polka-dotter will stop.
People have tried to make all kinds of perpetual motion machines. But the friction that slows the machines is always a little stronger than the forces the machines make to keep running. That is why perpetual motion does not work.
Picture Credit : Google