Archimedean buoyant force
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Statement of the law
Any object immersed in a fluid is buoyed up by a force equal to the weight of the fluid displaced by the object. This force is called Archimedean buoyant force.
A fluid is a deformable material environment, like a liquid or a gas.
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Physical formula
Archimedean buoyant force = Pfluid x V x G
Fluid density Immerged volume Gravity force
(kg/cm3) (m3) (N/kg)
G is the constant representing the gravitational force equal to
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Experiment to illustrate the phenomenon
Equipment: a ping-pong ball, a funnel, a water source
Protocol and observations:
→ The ping-pong ball is placed at the bottom of the funnel.
→ The funnel is filled with running water.
The water keeps running through the hole. The ball stays at the bottom of the funnel.
→ The hole of the funnel is blocked with a finger.
The water stops running through. The ball jumps and comes up to the surface.
Conclusion:
As soon as the ping-pong ball is entirely contained by water, it jumps to move back up to the surface. Indeed, water is a fluid and Archimedes' force is applied on the ping-pong ball as on any body contained in a fluid.
