Put your index fingers about \(1 \mathrm{~m}\) apart and rest a meterstick or similar object on top of them. Then, while holding the meterstick parallel to the floor, slowly draw your fingers toward each other. You will find that first one finger slips easily under the stick, then the other finger, then the first one again, then the other one again. No matter how much alternating takes place, however, your fingers always meet at the center of the stick. Explain what is happening.