# Pressure Facts

Pressure : It is the force divided by the area on which it acts, that is the force per unit area at any point determines the pressure at that point.

Pressure (p) = Force (F)/Area (A)

The pressure is a scaler quantity. Its units are N/m2. This unit is also called pascal(Pa)

Manometer : Instrument used to measure pressure of gas and vapour.

Altimeter : Sensitive instrument that indicates altitude.

Pascal’s law
The French scientist Blaise Pascal discovered in the 17th century that pressure applied any part of a liquid in a closed vessel is transmitted with equal intensity to all parts of the liquid and acts in all directions. This principle is known as Pascal’s law

Bernoulli’s principle-Fluids in motion
For continuous flow of liquid through a pipeline of nonuniform cross-section, the velocity of the liquid is greater in the narrow parts of the pipe. Bernoulli (1654-1705) Bob served a very interesting phenomenon. He found that in a liquid flow (this also holds true for gas flow), the pressure is lower in the region where the flow is faster and stop this is called Bernoulli’s principle.

This can also be stated as: When the speed of a fluid (liquid or gas) in a pipeline increases, the pressure decreases and conversely when the speed of a fluid decreases, the pressure increases.