Pressure Concepts

Pressure Definition Pressure is a measure of force that particles exert on one another.

Which gaseous system is under the greatest pressure? l l l l l l ll l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l A B C

Is gas a compressible or incompressible fluid? It is a compressible fluid. We can squeeze any container of gas to reduce its volume. This will increase the pressure inside the container.

How can you increase the pressure of a gas? Add more gas to the container. Decrease the volume of the container. Increase the temperature.

BIG IDEA IN SCIENCE! Particles under high pressure gravitate toward areas of lower pressure.

Your job… Use your knowledge of pressure concepts to explain the following phenomena.

Glass and water The air pressure in the glass is lower than the pressure in the room (because of the water). So the air in the room wants to move toward the glass, and pushes the card up.

Swimming at the bottom of a pool There is a lot of water above you, pushing down on you. Remember that water is heavy, so it will hurt if you have a lot of it above you.

Vacuum pump https://www.youtube.com/watch?v=QeAp3CuGjk8 Bill Nye’s friend can hang from the lid of the container because all the air has been pumped out of it. This means there is very low pressure in the container and higher pressure in the room. The difference in pressure is so extreme that it’s able to hold up the plate that he’s hanging from. When the pump is turned off and air is allowed back into the container, the pressure equalizes and he falls.

Stadium roof collapses High pressure inside the stadium, low pressure outside. When snow punctured the roof, the air rushed out toward the lower pressure area.

High altitudes

Why do planes fly?

High 5 demo

Air planes are pressurized https://www.youtube.com/watch?v=4yG2h1aDB6k