write short note on pressure
Answers
Answer:
The amount of force exerted (thrust) on a surface per unit area is defined as ‘Pressure’. It can also be defined as the ratio of the force to the area (over which the force is acting).
Formula and Unit of Pressure
Pressure (P) = Thrust/ Area
The SI unit is ‘pascals (Pa)’. 1 Pa = 1N/m2
Example: It is easier to hammer a sharp pin than to hammer a blunt pin. This is because the area at the end of the sharp pin is smaller than the area at the end of a blunt pin. This leads to an increase in pressure leading to hammer the sharp pin easily.
Types of Pressure
Atmospheric Pressure
Absolute Pressure
Differential Pressure
Gauge Pressure
Atmospheric Pressure
The earth’s atmospheric air is surrounded by a layer of gases and so this air surrounding the earth exerts a pressure known as the ‘atmospheric pressure’. Its value at sea level is 101325 Pa.
It is measured using a mercury barometer (hence atmospheric pressure is also known as barometric pressure), indicating the height of a column of mercury which exactly balances the weight of the column of atmosphere over the barometer. It can be expressed in several different systems of units such as millimeters (or inches) of mercury, pounds per square inch (psi), dynes per square centimeter, millibars (mb), standard atmospheres, or kilopascals.
The atmospheric pressure decreases near Earth’s surface, with height at a rate of about 3.5 millibars for every 30 meters (100 feet).
Check out our detailed article on Units of Pressure here.
Pressure on walls of the container
Pressure
The liquid at the bottom of the container (in which it is filled) exerts some pressure which depends upon the height of water filled in the container. The value of pressure exerted by the liquid at the side walls of the container; at any point depends upon the amount of water above that point. Since in a container the height of liquid above a surface is same for all the points, therefore, liquid exerts same pressure at a particular level.
Gases too exert pressure on the wall of the container containing them. A gas consists of molecules and every molecule has some kinetic energy. These molecules when colliding with the walls of a container, apply pressure on it.
Answer:
The force exerted perpendicularly on a unit area is called pressure
Explanation:
pressure =force /area on which the Force is applied