2.19 Confined Fluids Under Pressure Pages 124-125

What are Confined Fluids?

They are fluids that are in a closed system.

Examples:

Air in Air Mattress

Propane in propane tank

Paint in Spray Paint Can

Blood in the Body

What Happened Here?

When you apply force to one part of a fluid system, it results in movement in another part of that system.

This is the basis for hydraulics, pneumatics, etc.

The force is transmitted through the fluid to another

moveable part, usually some distance away

How Brakes on a Car Work

The driver pushes down on the brake pedal, which pushes brake fluid through the brake lines towards the wheels. The brake pedal pads are forced against the wheels to stop the car.

Back to the Particle Theory

e.g. : Propane inside the propane tanks is liquid propane

How do they do this? and WHY?

They do this because they can store more in a given area

when it is a liquid, and they do this by compressing(increasing pressure) the gas into a liquid

Gases, are usually stored as liquids.

How and Why Continued --The Particle Theory

Gas Liquid

Device toReduceVolume

Gas Liquid

Explanation of How to Compress Gas.....

Using the Particle Theory!

Gas particles are spread out as far as they can. By compressing

them, we are using something to physically move them closertogether.

We are decreasing the volume of the gas, while leaving the mass the same

As the particles are pushed closer and closer together,the attraction between particles occurs, and the fluid is forced into becoming a liquid

Forcing the particles of a gas closer together is called compression

The reason we compress gas, is to cram inmore of the fluid into the container. As we cramin more stuff (under pressure) the fluid may turnto a liquid.

Gases are very compressible

There is a cushion to them, that is why there is a delay in an air filled system…with your syringes it took a brief moment before the plunger on the other side moved.

Liquids are only slightly compressible.

So we call them incompressible

No delay to a water filled system… with your syringes the plunger on the other side moved right away.

Liquid Gas

Read pp. 124-125 if you need more information to answer the following questions.

• Questions:

page 125 # 1, 2, 3, 4, 5, 7