Archimedes’ Principle state that “ When an object is immersed in a fluid (a liquid or a gas) ,the buoyant force

( upthrust force) on the object is equal to the weight of fluid displaced by the object.

From Archimedes’s Principle :

Buoyant Force, Fb = Weight of fluid displace

= mg (note : F = ma)

= ρVg (note : ρ = m/V )

Thus Fb = ρ V g

Where Fb = Bouyant Force or Upthrust

ρ = Density of fluid

V = Volume of fluid displaced or the volume of the object that immersed in the fluid.

Equation for buoyant force

1. Buoyant force = Weight of fluid displaced

2. Buoyant force = ρVg

3. Buoyant force = Weight object in air – weight in water