Buoyancy Formula


It is apparent that kids are astonished when witnessing paper boats float in water. So what keeps these paper boats floating in the water. It is called Buoyancy

Buoyancy formula

Weight of displaced liquid = Buoyancy

Buoyancy is the phenomena stated by Archimedes which says the body experiences the upward force when it is completely or partially submerged in liquid.

The description of buoyancy denotes to whether something can float in air or water, or the power of water or other fluids to keep water afloat, or a positive disposition. An instance of example for buoyancy is when a boat floats over water. Buoyancy is an upward force applied by a fluid that opposes the weight of an immersed object.

 Buoyant Force is articulated by the following formulas:

Buoyant force Fb, in terms of pressure is articulated by

P = Pressure and
A = Area
In terms of Area Height and Volume, it is given by


the density of the fluid is ρ ,
the gravity is g,
volume of the immersed part of the body in the fluid is V.
the height of immersed part is h and
the area is A.
Buoyant force formula helps to determine

Buoyancy Formula Problems

Questions based on Buoyancy are provided below:

Problem 1: A ice cube having density of 0.5 g/cm3  has a Buoyant force of 9 N, is immersed in water. Calculate its Volume?

Density of ice ρρ = 0.5 g/cm3,
Buoyant force, Fb = 9 N,

Problem  2: A wooden log of density 2g/cm3 and volume 50 cm2 fall on the surface on water. Calculate its Buoyant force?

Given: Density ρ = 2 g/cm3,
Volume v = 50 cm2,
Buoyant force is given by Fb = ρρ g v
= 2 × 10-3 × 106 Kg/m3 × 9.8 m/s2 × 50 × 10-4 m2

= 98 N.



Practise This Question

Polyurethane is quite good for cold weather for jackets and blankets. However, thermal emergency blankets or space blankets are often made up of something similar to aluminum foil and used by astronauts to avoid hypothermia when stuck in subzero temperature. Why do you think it is a good choice?