Under pressure Flashcards
What is pressure?
It is the amount of force pushing against a given area. Its unit is N/m^2 or Pascal (Pa). Pressure = Force/Area
What is gas pressure?
It is the pressure that results from the collision of gas particles with an object. How much pressure a gas exerts depends on the amount of gas. The more gas particles there are the greater the pressure.
What are the gas laws?
They describe the relationship between the pressure, volume, and temperature of a given amount of gas. They are named after the scientist who discovered them
What is Boyle’s law
Discovered by Robert Boyle. If the temperature of a gas is held constant, increasing the volume of the gas decreases its pressure.
As volume increases, the pressure of the gas decreases because pressure and volume are inversely proportional.
What is Charles’s law?
Discovered by Jaques Charles. If the pressure of gas is held constant, increasing the temperature of gas increases its volume.
What is Amonton’s law?
Discovered by Guillaume Amontons. If the volume of a gas is held constant, increasing the temperature increases of a gas increases its pressure.
What is Bernoulli’s principle and its applications?
Bernoulli’s law states that the pressure of a moving fluid such as air is less when the fluid is moving faster. It explains how wings of airplanes or birds causes the air below them to move slow. This makes the pressure above lesser than the pressure below them keeping them above the ground. A spoiler on a car is a upside down wing
What is the atmosphere
The atmosphere is a blanket of gases that surrounds the planet. It protects and sustains life. The mixture of gasses in the atmosphere is called air.
What gasses are in the atmosphere?
- Nitrogen makes up about 78% of the earths atmosphere. It is released in the air by volcanoes and decaying matter.
- Oxygen makes up 21% of the Earth’s atmosphere. Humans and other living things need oxygen to survive
- The remaining 1% is made of 0.93% Argon and 0.04% CO2. The rest are trace gasses.
What is the nitrogen cycle
Nitrogen is used to make protein in living things. Nitrogen is changed to nitrogen containing molecules by bacteria in soil. Plants absorb the molecules and use them to make protein. Humans and animals eat the protein. Bacteria in the soil eventually return nitrogen to the atmosphere.
Atmosphere of Mercury, Venus, Earth, Mars
Mercury - No atmosphere
Venus - Atmosphere with 96% CO2
Earth - 78% Nitrogen
Mars - 95% CO2
How did oxygen enter the Earths atmosphere?
Organisms like plants used the energy of the sun to survive. This process is called photosynthesis and also used CO2. In this process they released oxygen filling up the atmosphere with it.
How is carbon stored?
Bodies of living things are mostly made up of carbon. Plants take in carbon from the atmosphere to build tissues. Carbon enters the atmosphere when organisms exhale and decompose. Long living organisms store carbon for long, when they die the carbon gets stored in the ground. Organisms also use carbon to make their shells. This helps make fossil fuels.
Pressure in the atmosphere
Atmospheric pressure is a measure of the force per unit area of air molecules in the atmosphere at a given altitude.
Molecules closest to Earth’s surface are packed together very densely. This is because the weight of the molecules above presses down, creating atmospheric pressure. The pressure is greatest at sea level
Altitude and air pressure
Altitude is a measure of the distance of an object above sea level. As the altitude increases, the density of the air molecules decreases as there are fewer molecules pushing down and a weaker gravitational pull.
How do we handle the atmospheric pressure
For humans the force exerted by our bodies counteracts the air pressure. For sea creatures to whom the pressure is more, have no air pockets and a jelly like body that functions well.
How is atmospheric pressure measured?
A barometer is an instrument that measures atmospheric pressure. Before mercury barometers were used. Mercury was placed in a bowl with a tube at one end. As the air pressure increased the mercury went higher up the tube. Since mercury is poisonous, we now use aneroid barometers. They hace a airtight cylinder made of thin metal, when pressure increases the wall squeeze inwards and vice versa.
What are the layers of the atmosphere?
- Troposphere
- Stratosphere
- Mesosphere
- Thermosphere (And ionosphere)
- Exophere
Describe the troposphere
We live in this layer. It extends till about 11 km. The troposphere is warmest closer to the earths surface. As u go up it becomes colder in this layer. This is the region where clouds form and where all weather happens. When airplanes fly above weather they are flying above this layer.
Describe the Stratosphere
It extends from about 11 to 50 km. The temperature increases as you go up because of a thin layer of ozone. The ozone layer is here. The ozone layer absorbs the UV rays.
Describe the mesosphere
It extends from about 50 to 80 km. The temperature starts to drop again. It is the coldest layer reaching as low as -90 degrees Celsius. Most meteors or shooting stars burn up in this layer.
Describe the thermosphere.
It begins at 80 km. It is the hottest layer. It has a low density of air molecules. The molecules have a lot of energy because the sun hits them first, creating high temperatures.
Describe the exosphere
The exopshere begins at about 500 km and doesn’t have a specific outer limit. Lightweight atoms and molecules escape into the space from this region. The satellites orbit over here. The orbit path is called the ClarkeBelt.
Describe the ionosphere
It is a part of the thermosphere. It is where the suns ultraviolet lights created charged atoms and molecules called ions. The energy released in this process causes high temperatures. Ions easily transmit electricity and electromagnetic waves making it possible for radio signals etc. to get signal.
How is the ozone layer becoming thinner?
CFC’s or chlorofluorocarbons are responsible for this. This gas stays intact until the stratosphere, over there they break down and release chlorine. The Chlorine reacts with ozone molecules leaving behind ordinary oxygen, which doesn’t block the income ultraviolet rays.
How does change in altitude affect pressure?
Air pressure decreases as altitude increases. The reasons for this are:
1. Most gas molecules in the atmosphere are pulled close to the Earths surface with gravity, so gas particles are denser near the surface. There are more particles in a given volume, resulting in more collisions with an object and greater pressure
- The depth of the atmosphere is greatest at sea level and decreases at higher altitudes. Which greater depth more air is pressing down from above.
