GREENVILLE, N.C. (WITN) – Eastern North Carolina science teacher Covey Denton is back on ENC At Three with two new Thanksgiving holiday experiments.
Inertia Pumpkin
Sir Isaac Newton described inertia in his first law of motion. He said an object at rest will stay at rest until an unbalanced force acts on it. When we have the stack of the vase, pie plate, tp roll and pumpkin, it is a balanced system. When we apply the force to the pie plate, the pie plate and lightweight tp roll move quickly out from under the pumpkin. The pumpkin, because it has more mass, lingers in the air just a split-second. With nothing underneath to support it, it falls perfectly into the vase, making a wonderful Thanksgiving centerpiece.
Speaking of the vase, we filled it up with a polymer bead from the florist. These beads will refract (bend) light under normal circumstances, but they bend light very similarly to water because they are 99% water. When we poured in the liquid, suddenly the little fall trinkets became visible because the water and the beads bent the light the same way and the edges of the beads seem to disappear.
Smoke Rings
In this experiment, we took a plastic cup with a hole cut in the bottom and stretched a plastic bag over the opening. When you hit the plastic bag, it forces the air to leave quickly through the hole, creating a vortex. A vortex is a circular shaped ring of spinning gasses that move together. To make the ring visible, you can hold the cup over a blown out candle to collect the smoke (or use a fog machine like we did).
When you force the air out through the hole, the air in the middle is moving much faster than the air that “trips” over the edge of the hole. This creates a spinning ring that can travel across the table to knock over the Styrofoam cups. Bernoulli is the scientist who described moving air and pressures. Faster moving air creates an area of low pressure, that low pressure is the force that helps the smoke ring hold together.
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