Engine engineering

What is a Pascal in Physics?

What is a Pascal in Physics?

The pascal (symbol: Pa) is a unit derived from the International System used to measure internal pressure, mechanical stress, Young's modulus and tensile strength. Pascal is defined as a newton per square meter.

The unit is named after Blaise Pascal, known for his contributions to hydrodynamics and hydrostatics, and experiments with a barometer. The name pascal was adopted for the SI Newton unit per square meter (N / m  2  ) by the 14th General Conference on Weights and Measures in 1971.

What is a Pascal equivalent to?

Next, we attach a Pascal conversion table to other pressure units:

  • 1 N / m 2  = 1 Pa
  • 101325 atm = 1 Pa
  • 100000 bar = 1 Pa
  • 9.80665 kg / m 2  = 1 Pa
  • 1 mm of water column (mm H 2 O) = 9.80665 Pa
  • 1 mm mercury column (mm Hg) = 133,322 Pa

Some common of the pascal are hectopascal (1 hPa = 100 Pa), which is equivalent to one millibar, quilopascal (1 kPa = 1000 Pa), megapascals (1 MPa = 1,000,000 Pa) and gigapascal (1 GPa = 1,000,000,000 Pa ).

The unit of measure called the standard atmosphere (atm) is defined as 101,325 Pa and approximates the atmospheric pressure at sea level at a latitude of 45 ° N.

In which examples is pascal used as a unit of measure?

Pascal (Pa) or kilopascal (kPa) as a unit of pressure measurement is widely used throughout the world and has largely replaced pounds per square inch (psi), except in some countries that still use the imperial measurement system or in the US UU.

Geophysicists use gigapascal (GPa) to measure or calculate tectonic tensions and pressures within the Earth.

Medical elastography measures tissue stiffness non-invasively with ultrasound or magnetic resonance imaging, and often shows Young's modulus or tissue shear modulus in kilopascals.

In materials science and engineering, pascal measures the stiffness, tensile strength and compressive strength of materials. In the use of engineering, because the pascal represents a very small amount, the megapascal (MPa) is the preferred unit for these uses.

The pascal is also equivalent to the unit of the international system of energy density measurements, J / m 3 . This applies not only to the thermodynamics of pressurized gases, but also to the energy density of electric, magnetic and gravitational fields.

In measurements of sound pressure or sound intensity, a pascal equals 94 decibels SPL.

The airtightness of the buildings is measured at 50 pascals (Pa).

The atmospheric pressure units commonly used in meteorology were previously the bar, which was close to the average air pressure on Earth, and the millibar. Since the introduction of the units of the international measurement system (SI), meteorologists generally measure the pressures in hectopascal units (hPa), equivalent to 100 pascals or 1 millibar.

Exceptions include Canada, which uses kilopascals (kPa). In many other fields of science, SI is preferred, which means that Pa with a prefix (in multiples of 1000) is preferred.

Many countries also use millibars or hectopascals to make adjustments to the aviation altimeter. In virtually all other fields, the kilopascal (1000 pascals) is used instead.

What is the Pascal principle?

Pascal's law (also the Pascal principle or the principle of fluid pressure transmission) is a principle in fluid mechanics given by Blaise Pascal which states that: "The pressure exerted on a liquid contained in a completely filled and closed container will continue to spread in all directions. "

In other words, Pascal's principle tells us that a change in pressure at any point of an incompressible confined fluid is transmitted through the fluid in such a way that the same change occurs everywhere.

Pascal's law is also called Pascal's principle or principle of fluid pressure transmission.

Who was Blaise Pascal?

Blaise Pascal (Clermont-Ferrand, June 19, 1623 - Paris, August 19, 1,662) was a philosopher, mathematician, physicist, inventor, writer, moralist, mystic and Occitan theologian, considered one of the brightest characters of wisdom Western and probably the only one that occupies front-line positions in the manuals of all the disciplines he cultivated.

What is a Pascal in Physics?

In his maturity, however, he approached Jansenism, and, faced with the prevailing rationalism, undertook the formulation of a philosophy of Christian sign (truncated by his premature death), in which his reflections on the human condition, especially who knew how to appreciate both his great dignity and his miserable insignificance.

Inventions and discoveries of Blaise Pascal

In 1642, inspired by the idea of ​​making his father's tax calculation job easier, Blaise Pascal began working on a calculator called Pascaline. (The German scholar William Schickard had developed and manufactured an earlier version of the calculator in 1623). Pascalina was a numerical wheel calculator with moving spheres, each representing a numerical digit. The invention, however, was not without technical problems: there was a discrepancy between the design of the calculator and the structure of the French currency at that time. Pascal continued working on the improvement of the device, with 50 prototypes produced in 1652, but Pascaline was never a great sales success.

In 1648, Pascal began writing more of his theorems in The Generation of Conic Sections, but pushed the work aside until the next decade.

At the end of the 1640s, Pascal temporarily focused his experiments on the physical sciences. Following in the footsteps of Evangelist Torricelli, Pascal experienced how atmospheric pressure could be estimated in terms of weight. In 1648, asking his brother-in-law to take barometric pressure readings at various altitudes on a mountain (Pascal was too poor to do the trek himself), he validated Torricelli's theory about the cause of barometric variations.

In the 1650s, Pascal dedicated himself to trying to create a perpetual motion machine, whose goal was to produce more energy than he used. In the process, he stumbled upon an accidental invention and in 1655 Pascal's roulette machine was born. Appropriately, he took his name from the French word for "little wheel."

The overlapping of his work on roulette was the correspondence of Pascal with the mathematical theoretician Pierre de Fermat, which began in 1654. Through his letters about the game and Pascal's own experiments, he discovered that there is a fixed probability of a result particular when it comes to the roll of the dice. This discovery was the basis of the mathematical theory of probability, with Pascal's writings on the subject published posthumously.

Although the specific dates are uncertain, Pascal also invented a primitive form of the wristwatch. It was an informal invention, to say the least: it was known that the mathematician put his pocket watch on his wrist with a piece of rope, presumably for convenience while retouching with other inventions.

Publication Date: September 5, 2017
Last Revision: February 27, 2020