Experiment lead: Hernan Paz and Amer
We started the day exploring the scientific method by examining Bernoulli’s principle. To demonstrate Bernoulli’s principle a ping-pong ball was levitated with a blow dryer. The class, having no knowledge of Bernoulli’s principle, formed hypotheses to explain the phenomenon they were observing. To test these different hypotheses, we changed to temperature of the system and altered the wind speeds. The class got rather close to the answer and in the end, we revealed that the ping-pong ball’s levitation was due to Bernoulli’s principle.
The focus of the day’s experiments was on weather, specifically the different effects of air pressure. The first experiment was to demonstrate the amount of force air can exert by crushing an aluminum can. This was achieved by heating a can with a small amount of water inside and then invert the can into an ice bath drastically decreasing the temperature. By creating a seal between the ice water and the open mouth of the can, the air inside was rapidly decreased in pressure causing the can to collapse. The next experiment looked at the effect air pressure has on the boiling point of water by using ice to boil water. We brought water in an Erlenmeyer flask to a boil, capped the flask with a rubber stopper, and inverted it onto a ring stand. Ice was place on the top of the now inverted flask which decreased the pressure in the flask without decreasing the temperature of the water too much. As the air pressure dropped below the vapor pressure of the heated water, the water in the flask began to boil again. The last experiment was the cloud in a bottle experiment, students pressurized 3 – 1 liter bottles containing acetone (nail polish remover), isopropyl alcohol (rubbing alcohol), and water using a bike pump. Releasing the pressure from the bottle allowed much of the vapor to condense and would produce a thick cloud dependent on the boiling point of the liquid. This experiment allowed students to learn about how clouds are formed and how properties of the liquid can affect their vapor pressure and subsequent ability to form clouds.