1. Pressure- Pascal’s Law
Atmospheric Pressure, Hydraulics and Pneumatics

2. Atmospheric Pressure
Atmospheric pressure is the amount of force that is exerted by the weight of the atmosphere.
As you climb higher in the atmosphere, the amount of air above you decreases. Therefore, the air exerts less pressure on you. The air pressure inside your body, however, does not change as quickly.

3. Atmospheric Pressure
Your eardrum is a very thin membrane that can move in response to a difference in air pressure. If the difference in pressure on either side of the eardrum becomes great, you experience a “pop” inside your ear as the pressure equalizes.

4. Pascal’s Law
Pascal’s law states that pressure applied to an enclosed fluid is transmitted with equal force throughout the entire container.

5. Pascal’s Law
Every time you squeeze a tube of toothpaste you demonstrate Pascal’s law. The pressure that your fingers exert at the bottom of the tube is transmitted through the toothpaste and forces the paste out at the top.

6. Hydraulics
Hydraulics is the study of pressure in liquids. Devices that transmit applied force through a liquid to move something else are called hydraulic systems.

7. Hydraulics
In most hydraulic systems, a force is exerted on a continuous, enclosed liquid.
This applied force creates pressure that moves the liquid through a series of tubes, pipes, or hoses, which causes a motion at the other end of a hydraulic system.

8. Hydraulics Examples of hydraulic systems:
a dentist’s or a hairdresser’s chair
the Jaws of Life that are used by fire departments
dump trucks

9. Liquids are a incompressible fluid (ie. definite volume).
As long as the liquid is enclosed in a tube or a pipe, the force will be transmitted along the liquid until something moves or bulges.

10. Pneumatic systems
Just like other fluids, air exerts pressure on everything that surrounds it. The study of pressure in gases is called pneumatics.
In pneumatic systems, a gas transmits a force exerted on the gas in an enclosed space.
Pneumatic systems are similar to hydraulic systems, except that gases are used instead of liquids.

11. Pascal’s Law :Hydraulics and Pneumatics
Pascal’s Law applies to both hydraulics and pneumatics:

12. Applications of Pascal’s Law
Using your resources find examples of Pascal’s law:

13. Complete the Following:
1. What is atmospheric pressure? 2. Why are gases compressible? 3. Why are solids and liquids incompressible? 4. Why do your ears “pop” as your altitude increases? 5. Define Pascal’s law. 6. What is a hydraulic system? 7. What is a pneumatic system? 8. Provide an example of a hydraulic system and a pneumatic system.