neither sinking nor moving vertically upwards), then the upthrust must be fully supporting the object’s weight. There is a so-called “apparent loss in weight”, because the buoyant force has supported some of the block’s weight. If one were to measure the weight of the solid block when it is immersed in the fluid, he will find that the weight of the block is less than that in air.

The downward arrow represent the weight of the block pulling it downwards and the upward arrow represent the upthrust pushing it upwards. In the figure on the left, there are arrows on the top and bottom of the solid block. The “apparent loss in weight” was not mentioned in my explanation. So, we can say thatĬompare this conclusion with the statement above summarising Archimedes' principle. Since V is the volume of fluid displaced, then the product of V, ρ and g is the weight of the fluid displaced. Furthermore, the pressure difference of the fluid acts only on the immersed part of an object. In any situation, the volume of fluid displaced (or the volume of the object submerged) is considered to calculate upthrust, because ( h 2 – h 1) is the height of the solid block only when it is completely immersed. So, ( h 2 – h 1) a is the volume of the solid block, V. The difference in the force exerted, d on the top and bottom surfaces with area a is due to the difference in pressure, given byīut ( h 2– h 1) is the height of the wooden block. On the figure on the left, a solid block is immersed completely in a fluid with density ρ. Let us confirm this principle theoretically.

After making this discovery, he is said to have leapt out of his bathtub and ran through the streets of Syracuse naked shouting 'Eureka!'.Īn object experiences upthrust due to the fact that the pressure exerted by a fluid on the lower surface of a body being greater than that on the top surface, since pressure increses with depth. When a body is completely or partially immersed in a fluid it experiences an upthrust, or an apparent loss in weight, which is equal to the weight of fluid displaced.According to a tale, Archimedes discovered this law while taking a bath. Archimedes' principle is a law that explains buoyancy or upthrust.

Archimedes principle explained