# Archimedes force

genius Archimedes grew up in a family of mathematics, received an excellent education in Alexandria and lived all his life in the Sicilian town of Syracuse.He was the founder of theoretical mechanics, successfully worked on the problem of finding the surface area and volume of various shapes and bodies.Often remember his famous phrase, "Give me a place to stand and I will move the Earth" and the exclamation "Eureka!" When he discovered the law named after his name.But in addition, he was an outstanding scientist in the field of geometry and mechanics, and engineering achievements of his contemporaries were amazing boldness of conception and great results.He built a catapult throwing vysokopritselnym system of its block-arm mechanism allows to lift the ship above the water, and they invented the block solntseotrazhayuschih mirrors burnt the Roman fleet during the siege of Syracuse.

Among other discoveries that connects history with the name of this brilliant scientist in physics will forever remain the Archimedes force.This finding was associated with the practical needs: required to determine the integrity of jewelers, to make the crown for the king Hiero II.What is now called the specific gravity, was already well known at the time, but how to determine the amount of such a complex product, it was not clear.Legend links the hard discovery of the law with the adoption of a scientist Archimedes bath.The essence of the discovery is that the body in the fluid acts buoyancy of Archimedes, the definition of which is the subject of special attention of designers swimming techniques, devices operating in liquids, under water, as well as objects aeronautics - balloons, probes, airships, etc..

classic formulation of the law states that Archimedes force equal to the weight of the liquid, which superseded immersed in her body.Under this definition formula signs very easy: if we assume that the volume of a body immersed in a fluid is equal to O, while the share of liquid - p, then their product is the desired Archimedes force.The formula to calculate it is written as follows:

Very often, it is tempting to put to the test Archimedes' principle in relation to the gas - too much different density of liquid and gas.For skeptics have a fairly simple experiment.In the box with the possibility of pumping air place on the scales a large bowl, for example, glass, and metal weights to balance it.

So, the weight of the ball in the air is balanced by the weight of the kettlebell and we can write the equality Pi = Pm satisfied, becausethings balanced.If initially assume that Archimedes' principle is valid, then the ball and the weight the force of Archimedes FS and FG, and then the equilibrium condition can be written differently:

Pm = Rsh1 - FSH and Pr = WG1 - FG, where Rsh1 and WG1 weight of the ball andweights in a vacuum.Then we proceed as taught in school: Rsh1 - PN = WG1 - FG, where Rsh1 WG1 = - = FH + FN + WG1 (F w - FG).

Now we need to - need to disclose the content of buoyancy forces to the ball and weights: PN = p * Osh and FY = p * Gr.

Making substitution values ​​buoyancy forces in the expression for Rsh1.

Rsh1 WG1 = - = FH + FN WG 1 + (p * Osh - p * Gr) = WG 1 + p * (Osh - Og).

Finally, we get to the weight of a ball in a void expression, which, given the fact that the Osh & gt;Oz, left no doubt: the weight of a ball in a vacuum greater than the weight of the kettlebell, but in the air they are balanced: Rsh1 WG1 = + p * (Osh - Og).

reason for this conclusion is that the Archimedes force depends on the specific weight of the air and the volume of a sphere.In this case, check this conclusion is very simple - it is necessary to pump the air out of the box.If you do this, you can verify firsthand that the law is the law, and it is done anytime, anywhere - both in liquid and in gas.Proof of this is omitted, the previously balanced weights, ball.

Device whose very existence - a continuous demonstration of Archimedes' principle in all its forms, is a submarine.Adjusting the weight vessel for the implementation of all the options move with the help of the ballast tanks - a vivid example of the use in practice is very ancient discoveries in modern conditions.