Fluids, Density, and Pressure (Part 1) - Physics LibreTexts
ling is caused by the work done by compression/expansion AND by Answer: The ideal gas equation. and the molar density of the rest of the air, nd. pressure excerted by the vapor molecules, e, and the partial pressure excerted by the. Temperature–viscosity relationship for liquid water at atmospheric pressure. Data (+, n = 11) per Lide (). Equations fitted to those data are;. In this equation, (P) represents pressure, (V) represents volume, and (k) is a constant. As you put more and more air into the tire, you are forcing all the gas . the volume of the lung cavity and decreasing the pressure within. . the pressure thanks to fluid dynamics flow, causing the density of the fluid.
You may have noticed your ears "popping" when flying, driving in the mountains, or even going up and down in elevators.Density Alititude - Flight Training Video
This is because our ears have an air space in them, and air, like all other gases, is compressible. A gas will compress proportionately to the amount of pressure exerted on it.
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- Boyle's Law Examples in Real Life
This theory was discovered by Sir Robert Boyle, a 17th century scientist. The theory known as Boyle's Law states: If the temperature remains constant, the volume of a given mass of gas is inversely proportional to the absolute pressure. Let's follow an example Suppose you had a balloon measuring one cubic foot at the surface of the water.
This balloon is under 1 ATM If we push the balloon underwater, and take it to a depth of 33 feet, it is now under 2 ATM of pressure Boyle's Law then tells us that since we have twice the absolute pressure, the volume of the balloon will be decreased to one half.
If we bring the balloon in the previous example back up to the surface, it would increase in size due to the lessening pressure until it reached the surface and returned to its one cubic foot size. This is because the air in the balloon is compressed from the pressure when submerged, but returns to its normal size and pressure when it returns to the surface.
We will achieve the same result with an open container, such as an inverted bottle, as we do with a balloon.
Intro to Boyle's Law
By inverting a bottle at the surface and descending with it, the pressure from the surrounding water will compress the air and the bottle will start to fill with water.
Even with no air escaping, the container will be half full of water at a depth of 33 feet due to the pressure compressing the air to half its original volume. Along with the volume of air in the balloon or container, the surrounding pressure will affect the density of the air as well.
Density, simply stated, is how close the air molecules are packed together. The air in the balloon or container at the surface is at its standard density, but when we descend to the foot level where its volume is reduced to one half, the density has doubled.
14.1: Fluids, Density, and Pressure (Part 1)
Once you've managed to gather these supplies, follow the steps below. Take your eyedropper, the "diver," and fill it with just enough water so that the top of the dropper is just buoyant enough to float on top of the water.
Apply the lid to the 2-liter bottle. It must be airtight! If you have successfully followed the instructions, your Cartesian diver should dive to the bottom as you squeeze the bottle.
That's Boyle's law in action! When you squeeze inward, you are reducing the volume of the bottle. As we know, this reduction in volume increases the pressure.
This increase in pressure pushes against the water, forcing more water up into the eyedropper. This additional water decreases the diver's buoyancy, causing it to "dive" to the bottom.
Stop squeezing the bottle, and your diver will ascend back to the water's surface. Since it is hard to exactly describe a real gas, scientists created the concept of an ideal gas. The ideal gas law refers to a hypothetical gas that follows the rules listed below: Ideal gas molecules do not attract or repel each other.
Pressure, Temperature, and RMS Speed - Physics LibreTexts
The only interaction between ideal gas molecules would be an elastic collision with each other or with the walls of the container. Ideal gas molecules themselves take up no volume. While the gas takes up volume, the ideal gas molecules are considered point particles that have no volume. There are no gasses that are exactly ideal, but there are many that are close. This is why the ideal gas law is extremely useful when used as an approximation for many situations.
2.2: Pressure, Temperature, and RMS Speed
The ideal gas law is obtained by combining Boyle's law, Charle's law, and Gay-Lussac's Law, three of the major gas laws. What Is Charle's Law?
Charle's law, or the law of volumes, was discovered in by Jaques Charles and states that for a give mass of an ideal gas at constant pressure, the volume is directly proportional to it's absolute temperature.