Let us suppose force F is applied normally to an area of A and pressure P is produced which is shown in figure.
We know that ,
pressure is directly proportinal to force applied for constant area.
that is P∝F ........... (i)
pressure is inversely proportional to the area A of a contact for a constant force applied.
P ∝ 1/A .......... (ii)
Combining the equation from the above statements (i) and (ii)
We get ,
P∝ F/A
or P= kF/ A where k is the proportionality constant and its value is 1 in unit system.
P= 1F/A
P = F/A
Hence proved.