ARCHIMEDES' PRINCIPLE
What is Archimedes' Principle?
Archimedes' principle states that the upward buoyant force that is exerted on a body immersed in a fluid, whether fully or partially submerged, is equal to the weight of the fluid that the body displaces and acts in the upward direction at the center of mass of the displaced fluid. Archimedes' principle is a law of physics fundamental to fluid mechanics. It was formulated by Archimedes of Syracuse. Archimedes' principle does not consider the surface tension (capillarity) acting on the body. Moreover, Archimedes' principle has been found to break down in complex fluids.
Fb = ρgV = ρghA
Fb = buoyant force of a liquid acting on an object (N)
ρ = density of the liquid(kg/m3)
g = gravitational acceleration(9.80 m/s2)
V = volume of liquid displaced (m3 or liters, where 1 m3 = 1000 L)
h = height of water displaced by a floating object(m)
A = surface area of a floating object(m2)
Buoyancy Formula Questions:
1. A golden crown has been placed in a tub of water. The volume of water displaced is measured to be 1.50 liters. The density of water is 1000 kg/m3, or 1.000 kg/L. What is the buoyant force acting on the crown?
Answer:
The buoyant force can be found using the formula. First, we ensure that the units used for volume are the same. If 1 m^3 = 1000 L, then 1.50 L = 0.00150 m^3. The buoyant force is:
Fb = ρgV
Fb = (1000 kg/m^3)(9.80 m/s2)(0.00150 m^3)
Fb = 14.7 kg∙m/s^2
Fb = 14.7 N
The buoyant force acting on the golden crown is 14.7 N