Poiseuille’s Law

Examples of Poiseuille’s Law in the following topics:

• Pressure in the Body

  • One particularly common and dangerous circulatory system condition is partial blockage of blood vessels due to a number of factors, such as plaque build-up from high cholesterol, which results in a reduction of the effective blood vessel cross-sectional diameter and a corresponding reduction in blood flow rate and thus an increase in blood pressure to restore normal blood flow according to Poiseuille's Law.
  • The mechanism resulting in inhalation is due to lowering of the diaphragm, which increases the volume of the thoracic cavity surrounding the lungs, thus lowering its pressure as determined by the ideal gas law.

• Flow Rate and Velocity

  • In the case of Laminar flow, however, fluid flow is much simpler and flow velocity can be accurately calculated using Poiseuille's Law.

• Poiseuille's Equation and Viscosity

  • Poiseuille's equation can be used to determine the pressure drop of a constant viscosity fluid exhibiting laminar flow through a rigid pipe.
  • For such a system with a pipe radius of r, fluid viscosity η, distance between the two points along the pipe Δx = x2 – x1, and the volumetric flow rate Q, of the fluid, the pressure difference between the two points along the pipe Δp is given by Poiseuille's equation (see ).
  • In practice, Poiseuille's equation holds for most systems involving laminar flow of a fluid, except at regions where features disrupting laminar flow, such as at the ends of a pipe, are present.
  • Poiseuille's equation as given in this example (see ) is analogous to Ohm's equation for determining the resistance in an electronic circuit and is of great practical use in hydraulic-circuit analysis.

• Gauss's Law

  • Gauss's law is a law relating the distribution of electric charge to the resulting electric field.
  • Gauss's law can be used to derive Coulomb's law, and vice versa.
  • In fact, Gauss's law does hold for moving charges, and in this respect Gauss's law is more general than Coulomb's law.
  • Gauss's law has a close mathematical similarity with a number of laws in other areas of physics, such as Gauss's law for magnetism and Gauss's law for gravity.
  • In fact, any "inverse-square law" can be formulated in a way similar to Gauss's law: For example, Gauss's law itself is essentially equivalent to the inverse-square Coulomb's law, and Gauss's law for gravity is essentially equivalent to the inverse-square Newton's law of gravity.

• Common Law

  • Law of the United States was mainly derived from the common law system of English law.
  • At both the federal and state levels, the law of the United States was mainly derived from the common law system of English law , which was in force at the time of the Revolutionary War.
  • American judges, like common law judges elsewhere, not only apply the law, they also make the law.
  • As a result, the laws of any given state invariably differ from the laws of its sister states.
  • Instead, it must be regarded as 50 separate systems of tort law, family law, property law, contract law, criminal law, and so on.

• Civil Law and Criminal Law

  • Criminal law is the body of law that relates to crime and civil law deals with disputes between organizations and individuals.
  • Criminal law is the body of law that relates to crime.
  • Criminal law also sets out the punishment to be imposed on people who do not obey these laws.
  • The law relating to civil wrongs and quasi-contract is part of civil law.
  • The objectives of civil law are different from other types of law.

• Primary Sources of American Law

  • The primary sources of American Law are: constitutional law, statutory law, treaties, administrative regulations, and the common law.
  • These sources are constitutional law, statutory law, treaties, administrative regulations, and the common law.
  • At both the federal and state levels, the law of the United States was originally largely derived from the common law system of English law, which was in force at the time of the Revolutionary War.
  • Thus, most U.S. law consists primarily of state law, which can and does vary greatly from one state to the next.
  • First, all U.S. states except Louisiana have enacted "reception statutes" which generally state that the common law of England (particularly judge-made law) is the law of the state to the extent that it is not repugnant to domestic law or indigenous conditions.

• The Law of Multiple Proportions

  • The law of multiple proportions states that elements combine in small whole number ratios to form compounds.
  • The law of multiple proportions, also known as Dalton's law, was proposed by the English chemist and meteorologist John Dalton in his 1804 work, A New System of Chemical Philosophy.
  • The law, which was based on Dalton's observations of the reactions of atmospheric gases, states that when elements form compounds, the proportions of the elements in those chemical compounds can be expressed in small whole number ratios.
  • Dalton's law of multiple proportions is part of the basis for modern atomic theory, along with Joseph Proust's law of definite composition (which states that compounds are formed by defined mass ratios of reacting elements) and the law of conservation of mass that was proposed by Antoine Lavoisier.
  • These laws paved the way for our current understanding of atomic structure and composition, including concepts like molecular or chemical formulas.

• The Law of Definite Composition

  • The law of definite composition states that chemical compounds are composed of a fixed ratio of elements as determined by mass.
  • In 1806, Proust summarized his observations in what is now called Proust's Law.
  • There are some exceptions to the law of definite composition.
  • In addition, the law of definite composition does not account for isotopic mixtures.
  • This video examines the law of definite proportions and the law of multiple proportions.

• [PF content: Differences in State Laws]