|MadSci Network: Engineering|
Hydro - static: Hydro comes from water. Static means it isn't moving. Hydrostatic pressure is simply what happens when the force of gravity pulls down on a liquid (water for example) while this liquid sits still (or is held back on purpose). This is happenning all the time, because gravity is always there. So if you look around you for places where a liquid is sitting still you will see: 1. Lakes 2. Oceans 3. Big water tanks 4. Dams 4. A glass of water But your question is not to simply to find where can we observe hydrostatic pressure, but also, where do we *USE* it. To answer that, we must look at how hydrostatic pressure works. Because liquids are pulled down by gravity, the more liquid you have, the heavier it is, since it has a greater mass. If it wasn't for a barrier holding the liquid, it would spill over. This tendency to spill over is one of the many effects we can see from hydrostatic pressure. Although, spilling things is not very useful... But one useful application would be to use this force to do work. To do work, you will first hold the liquid back into a tank or dam. Some time later you will have to let some of the liquid move, so it will not always be static. By holding large amounts of water back behind a dam, and then letting it spill slowly thru turbines, electricity can be generated thanks to hydrostatic pressure. Another way to use hydrostatic pressure, is by building a water tank that is sitting very high up. Some towns put their drinking water tanks at the top of a mountain or at the top of a tower. That way, the hydrostatic pressure will push water to the houses of people, with little or no help from mechanical pumps. The same principle is used at hospitals, where a patient has a catheter (the clear plastic bag with water and nutrients) and this catheter is placed much higher up than the patient, so hydrostatic presure will push the water and nutrients into the patients bloodstream. Now, even simpler than that is using hydrostatic pressure witouht letting the liquid move. A buoy is a good example. Buoys are built by making a sealed cavity full of air, foam or anything less dense than the liquid you want to use it with. Because a buoy is less dense, it is more lightweight than the amount of water it pushes out of its way. So the water pushes right back on it, and keeps it floating. Here are some good examples of buoys in use 1. The toilet in your house: The buoy inside it is attached to a water valve to stop water when the toilet is full. 2. Boats: Boats are simply large buoys used to carry people or things 3. Lifesavers: a buoy made to help people float in the water. And it is not just water. Any liquid generates hydrostatic pressure, alcohol, gasoline, you name it! Different liquids generate different amounts of pressure at a given depth. For example, people can float more easily in salt water, than in sweet water, because salt water is more dense. If you look around you you may find more examples of buoyancy and hydrostatic pressure. Just look where liquids are sitting still! Aurelio R. Ramos, your mad scientist.
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