Pressure
What is pressure and it's S.I unit?
Pressure is defined as the force acting per unit area.
P = F/A
S.I unit of pressure is Newton per square meter (N.m2) also known as pascal.
When area is smaller so high pressure is exerted.
When area is larger so less pressure is exerted.
Earth Gravitational pull:
The earth gravitational pull acts on all objects, including liquids,this causes liquids to have a weight
Pressure in Liquids:
A body of a liquid exerts pressure on an object place in it because of its weight.
The amount of pressure inside a body of liquid increases with the depth.
At greater depths,the weight of a liquid increases with depth.Therefore the pressure is greater.
P=hpg
Here P is pressure, h is height of column, p is density of liquid and g is gravitational field strength.
Pressure in liquid increases with depth and density of the liquid.
Hydraulic machines work on the basis of liquid used to transmit pressure.
Pascal's Law:
Pascal's Law states that if pressure is applied to an enclosed liquid, the pressure transmitted equally in all directions.
When small force is applied to small piston, it results in a larger force acting on bottom of larger piston. This allows large loads to be lifted.
Atmospheric pressure
The atmosphere exerts a pressure on earth surface and on everything on earth including us. This is known as atmospheric pressure.
The natural pressure with in human body is about 1 atmosphere (1.013 x 10 5 Pa) . Thus the internal pressure of our body is equal to atmosphere pressure that act on us.
A mercury barometer uses the height of a mercury column to measure atmospheric pressure.
The unit of measurement is mm Hg or cm Hg.
The manometer is used to measure the differences in the pressure of liquids and gases.
