FLUID PRESSURE AT A POINT & PASCAL'S LAW

FLUID PRESSURE AT A POINT. 

                       Consider a small area dA in large mass of fluid. If the fluid is stationary, then the force exerted by the surrounding fluid on the area dA will always be perpendicular to the surface dA. Let dF is the force acting on the area dA in the normal direction. Then the ratio of (dF/dA) is known as the intensity of pressure or simply pressure and this ratio is represented by p. Hence mathematically the pressure at a point in a fluid at rest is 

                                      p = dF /dA.

 If the force (F)  is uniformly distributed over the area (A)  , then the pressure is given by

                            p = F /A = Force /Area  . 

So,      Force or pressure force, 

                                     F =  p ×A  . 

The units of pressure are : (1) kgf /m² and kgf /cm² in MKS units, (2)  Newton /m² and N /mm² in SI units. N /m² is known as Pascal and is represented by Pa. Other commonly used units of pressure are MPa ( Mega pascal) , kPa ( kilo pascal) and bar . 

PASCAL'S LAW. 

                          It states that the pressure or intensity of pressure at a point in a static fluid is equal in all directions. This is proved as :

       The fluid element is of very small dimensions i.e. , dx, dy and ds. 

Page -1 ( PASCAL'S law) 

and the rest part is : 

 

Page -2 (PASCAL'S law)

                                     The End. 

    Please comment if you have any query. 

Disclaimer : An attempt has been made to make this blog error free. If there is any error, please forgive.

       



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