THE WATER HOLE
(Problem-Solving)
If we travel back in time to the place where dinosaurs roamed the land, we would be able to see a type of animal that is very similar to what we know as elephants today. This animal, however, differed in several ways to the elephant of today. It was very much larger (about five times), and it had two trunks. We call it the elephantwo.
The elephantwos became extinct around the same time the dinosaurs did, and there is a very strange reason as to why they did.
Water was a problem that faced many of these animals. The water supply was running low and the water that was to be found was contaminated. Therefore, they began to die. Fortunately, there was one elephantwo that was searching for water when it came upon a hole in the ground. It was similar to a spring, filled with crystal clear water. The hole, however, was only big enough to fit one trunk in. Alas, the elephantwo died of dehydration.
Why do you think the elephantwo died when it was able to get at least one of its’ trunks in the hole?
PROBLEM
Why can’t you suck water through two straws?
Remember – one straw is in the water, but the other is not.
EXPLANATION – The open straw keeps you from forming a vacuum pump with your mouth. Vacuum pumps won’t work if they are not airtight. The straw is a leak in the system. Since the pressure in your mouth remains the same as the atmospheric pressure, the drink stays in the glass.
When we suck a liquid through a straw, we do not actually pull the liquid up through the straw. Instead, by sucking on the straw, we remove some of the air from inside it. As a result, the air pressure inside the straw becomes less than the pressure of the air on the liquid outside the straw. The greater pressure of the air outside then pushes the liquid in the glass up through the straw and into our mouths.