What is Archimedes’ Principle

Archimedes’ Principle

Archimedes’ principle states that the buoyant force on a submerged object is equal to the weight of the fluid it displaces.

Example:- Consider a given object submerged in fluid.

Fig. Archimedes’ Principle

• let

P₁ = the pressure on the top of the object 

P₂ = the pressure on the bottom =P₁ + ρgh.

• If the area of top and bottom of the object is the same A,

∴ The force on the top  = P₁A  which acts downward,

the force on the bottom = P₂A which is act upwards.

• ∴  The net force on the object 

F = (P₂ - P₁)A = ρghA = ρgV = m_f * g

• where

m = the mass of the water which is displaced by the object

• This Archimedes’ Principle is the same for any shape of the object.
• Thus the buoyancy force is given by the weight of the fluid displaced is

F = mfg