Introduction about Units of Pressure:
Unites of Pressure pressure p in pascals exists on an object or region whose surface area is A meters squared, then the force F, in newtons, required to produce p is given by the following formula:watch Introduction about Units of Pressure to learn more.
F = pA
Units of Pressure:
They move rapidly and randomly, they don’t interact with each other, they have elastic collisions (meaning they don’t lose energy when they collide), and they are point particles (meaning the individual particles don’t have any volume).
Just like when you travel to a foreign country and have to use a different currency or different units to measure things, Johnny must use different units on Ideal Island. Today we are going to discuss pressure and the pressure units that are used here on the island.
I want you to think about the last time you measured the pressure of something. It may have been the pressure of the air in your car tires. Do you remember what it was? The air in my car’s tires is 32 psi. Psirepresents the pounds per square inch, which is a common unit for pressure. Let’s look a little more closely at ‘pounds per square inch.’ Weight is just the force of gravity’s pull on an object measure it in pounds.
This is one of many different units that can be used to measure pressure, and it’s probably the one that you use most on a daily basis in the United States. But on Ideal Island, different units are used, so it’s important to know what they are and how to convert among them. On the island, the most common units of pressure that are used are atmospheres (atm) and millimeters of mercury (mmHg). 1 atmosphere is often abbreviated as atm, and it’s really just the weight of all of the air above you ‘pressing down’ on you while you stand at sea level. Now, if you were on a mountain, there would be less air ‘pressing down’ on you, so the pressure would be lower (less than 1 atmosphere).
Millimeters of Mercury:
The unit millimeters of mercury (mmHg) goes back to the device used to measure pressure, the barometer. In this barometer, we have an inverted tube containing a column of mercury with the chemical symbol Hg, and it’s sitting in a pool of mercury. As the atmosphere ‘presses down’ on the mercury pool, the liquid extends up into the inverted tube, and the height is measured in millimeters (or some other length measurement). So if the weather is changing, resulting in an increase in the barometric pressure, the increase is measured by how far up the mercury extends in the column. At sea level, the mercury extends about 760 millimeters up the column.
Subject : Physics
Lesson : Gravitation
Topic:Units of Pressure
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