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In the physical sciences , Pascal's law or the Principle of transmission of fluid-pressure states that "pressure exerted anywhere in a confined incompressible fluid istransmitted equally in all directions throughout the fluid such that the pressure ratio (initialdifference) remains same."

whereΔP is the hydrostatic pressure (given in pascals in the SI system ), or the difference inpressure at two points within a fluid column, due to the weight of the fluid;ρ is the fluid density (in kilograms per cubic meter in the SI system);g is acceleration due to gravity (normally using the sea level acceleration due toEarth's gravity in meters per second squared );Δh is the height of fluid above the point of measurement, or the difference inelevation between the two points within the fluid column (in meters in SI).

The intuitive explanation of this formula is that the change in pressurebetween two elevations is due to the weight of the fluid between the elevations.

Note that the variation with height does not depend on any additionalpressures. Therefore Pascal's law can be interpreted as saying that any change inpressure applied at any given point of the fluid is transmitted undiminishedthroughout the fluid. Equation: (P 1)(V 1) = (P 2)(V 2) Pascal's Principle

P=F/A or F/A = F/A

Pascal's principle : Pressure applied to an enclosed fluid is transmitted undiminished toevery part of the fluid, as well as to the walls of the container.

Examples:

• When a person dives underwater for every 33 feet you dive down in the water, 1atmosphere of pressure is added. That is 14.7 pounds/square inch.

• Pressure is transmitted throughout fluid equally.

• Examples: squeezing a toothpaste tube, a shampoo bottle, a balloon that is blown upand squeezed.

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Units : Pa- Pascals cm3-centimeteres cubed n-newtons atm-atmosphere Torr-torr

• A common example of how Pascal's law is used in everyday life are the hydrolicsused to lift a car while its being worked on. Or the hydrolics that some peoploe putin their cars so that they bounce.

• A small force is applied to a small-area piston it is then transfered to a large force ata large-area piston. This causes it to become unbalanced and move up and down.

Bernoulli's principle can be applied to various types of fluid flow, resulting in whatis loosely denoted as Bernoulli's equation. In fact, there are different forms of the Bernoulliequation for different types of flow. The simple form of Bernoulli's principle is valid forincompressible flows (e.g. most liquid flows) and also for compressible flows (e.g. gases )moving at low Mach numbers . More advanced forms may in some cases be applied tocompressible flows at higher Mach numbers (see the derivations of the Bernoulli equation ).

Blaise Pascal

Full name Blaise Pascal

BornJune 19, 1623

Clermont-Ferrand, France

Died

August 19, 1662 (aged 39)

Paris , France

Era 17th-century philosophy

Region Western Philosophy

SchoolContinental Philosophy , precursor to

existentialism

Main

interestsTheology , Mathematics

Notable

ideas

Pascal's Wager , Pascal's triangle, Pascal's

law, Pascal's theorem

Daniel Bernoulli

Daniel Bernoulli

Born 8 February 1700

Groningen, Netherlands

Died 8 March 1782 (aged 82)

Basel , Switzerland

Residence unknown

Known for Bernoulli's Principle, early Kinetic theory of gases,

Thermodynamics

Signature

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Bernoulli's principle can be derived from the principle of conservation of energy .This states that, in a steady flow, the sum of all forms of mechanical energy in a fluid alonga streamline is the same at all points on that streamline. This requires that the sum of kinetic energy and potential energy remain constant. If the fluid is flowing out of a reservoirthe sum of all forms of energy is the same on all streamlines because in a reservoir theenergy per unit mass (the sum of pressure and gravitational potential ρ g h ) is the sameeverywhere. [4]

Fluid particles are subject only to pressure and their own weight. If a fluid isflowing horizontally and along a section of a streamline, where the speed increases it canonly be because the fluid on that section has moved from a region of higher pressure to aregion of lower pressure; and if its speed decreases, it can only be because it has movedfrom a region of lower pressure to a region of higher pressure. Consequently, within a fluidflowing horizontally, the highest speed occurs where the pressure is lowest, and the lowestspeed occurs where the pressure is highest.

Archimedes' principle, principle that states that a body immersed in a fluid isbuoyed up by a force equal to the weight of the displaced fluid. The principle applies to bothfloating and submerged bodies and to all fluids, i.e., liquids and gases. It explains not onlythe buoyancy of ships and other vessels in water but also the rise of a balloon in the air andthe apparent loss of weight of objects underwater. In determining whether a given body willfloat in a given fluid, both weight and volume must be considered; that is, the relativedensity , or weight per unit of volume, of the body compared to the fluid determines thebuoyant force. If the body is less dense than the fluid, it will float or, in the case of a balloon,it will rise. If the body is denser than the fluid, it will sink. Relative density also determinesthe proportion of a floating body that will be submerged in a fluid. If the body is two thirdsas dense as the fluid, then two thirds of its volume will be submerged, displacing in theprocess a volume of fluid whose weight is equal to the entire weight of the body. In the caseof a submerged body, the apparent weight of the body is equal to its weight in air less theweight of an equal volume of fluid. The fluid most often encountered in applications of Archimedes' principle is water, and the specific gravity of a substance is a convenientmeasure of its relative density compared to water. In calculating the buoyant force on abody, however, one must also take into account the shape and position of the body. A steelrowboat placed on end into the water will sink because the density of steel is much greaterthan that of water. However, in its normal, keel-down position, the effective volume of theboat includes all the air inside it, so that its average density is then less than that of water,and as a result

Hooke's law describes how far the spring will stretch with a specific force

In mechanics , and physics, Hooke's law of elasticity is an approximation that states

that the extension of a spring is in direct proportion with the load applied to it. Manymaterials obey this law as long as the load does not exceed the material's elastic limit .Materials for which Hooke's law is a useful approximation are known as linear-elastic or"Hookean" materials. Hooke's law in simple terms says that strain is directly proportionalto stress.

Mathematically, Hooke's law states that

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where x is the displacement of the end of the spring from its equilibrium position (in SI units: "m");F is the restoring force exerted by the material (in SI units: "N" or kgms -2 orkgm/s 2); andk is a constant called the rate or spring constant (in SI units: "N·m -1" or "kgs -2" orkg/s 2).

When this holds, the behavior is said to be linear . If shown on a graph, the lineshould show a direct variation . There is a negative sign on the right hand side of theequation because the restoring force always acts in the opposite direction of thedisplacement (for example, when a spring is stretched to the left, it pulls back to the right).

Hooke's law is named after the 17th century British physicist Robert Hooke . Hefirst stated this law in 1660 as a Latin anagram, [1] whose solution he published in 1678 as Ut tensio, sic vis , meaning, "As the extension, so the force".

Elastic

Objects that quickly regain their original shape after being deformed by a force, with themolecules or atoms of their material returning to the initial state of stable equilibrium, oftenobey Hooke's law.

We may view a rod of any elastic material as a linear spring. The rod has length L andcross-sectional area A. Its extension (strain) is linearly proportional to its tensile stress σ , bya constant factor, the inverse of its modulus of elasticity, E , hence,

or

Hooke's law only holds for some materials under certain loading conditions. Steelexhibits linear-elastic behavior in most engineering applications; Hooke's law is valid for itthroughout its elastic range (i.e., for stresses below the yield strength ). For some othermaterials, such as aluminium , Hooke's law is only valid for a portion of the elastic range.For these materials a proportional limit stress is defined, below which the errors associatedwith the linear approximation are negligible.

MRS. LOGMAO

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Archimedes Thoughtful by Fetti (1620)

Born

c . 287 BC

Syracuse, Sicily

Magna Graecia

Died

c . 212 BC (aged

around 75)

Syracuse

Residence Syracuse, Sicily

Fields

Mathematics ,

Physics ,

Engineering,

Astronomy,

Invention

Known for

Archimedes'

Principle,

Archimedes' screw,

Hydrostatics ,

Levers ,Infinitesimals

Robert Hooke

Portrait of Hooke, 2004.

Born18 July 1635

Freshwater, Isle of

Wight , England

Died3 March 1703 (aged 67)

London, England

Fields Physics and chemistry

Institutions Oxford University

Alma mater Christ Church, OxfordAcademicadvisors Robert Boyle

Known forHooke's LawMicroscopy

applied the word 'cell'

Influences Richard Busby