Common conversions among different pressure units Meteorologists also use the unit to measure air pressure, which is usually expressed in hectopascal. Material scientists use it to measure the elasticity, stiffness, tensile strength and compressive strengths of different materials. Geophysicists use the unit to study tectonic stresses acting on the Earth's plates. For measuring midrange pressures, higher pascal units, such as kilopascal, megapascal and hectopascal (hPa) are used. Uses of pascalĪ pascal is useful for ultralow gas pressure applications, such as ventilation systems where pressure differences need to be measured. Additionally, the unit is independent of other factors, such as ambient temperature, media density or local gravity. Unlike units such as PSI where the pressure value may vary, the pressure value represented by 1 Pa remains unchanged, regardless of where it is used. But, in most other countries that use metric and SI measurements, the pascal is used to measure pressure. In some countries, such as the U.S., pressure is expressed as pounds per square inch ( PSI). The pascal is used to measure this value and to understand if a material is elastic or not and to what extent. If Young's modulus is high, the material is less elastic and vice versa. When compression or tension is applied to the modulus, the material is either elastic or inelastic - or some version between these properties. Young's modulus is a mathematical constant that describes the elasticity of solid materials. This explains why a small pin or screw can penetrate a concrete wall when only a small or moderate force is applied, but a human thumb fails to do the same even if the force applied is larger. Since pressure and surface area are inversely related, an object of a smaller surface area generates a higher pressure than a larger object. Using this data, pressure can be calculated as follows: The surface area that the object makes with the wall is 0.0008 m 2. Here is an example of how pressure is measured in pascal.Ĭonsider an object being pushed against a wall with a force of 400 N.
A principle in fluid mechanics, it states that a change in pressure in a fluid creates the same change everywhere within the body of the fluid. Larger pascal units are expressed as follows:īlaise Pascal is also the namesake behind the well-known Pascal's law, which is used to develop hydraulic systems. Reduced to base units in SI, 1 Pa is 1 kilogram per m/s 2 - that is, 1 Pa = 1 kg x m -1 x s -2. 1 Pa = 1 N / m 2 = 1 N x m -2 or 1 N per m 2.If F is measured in newtons and A in square meters, a pascal can be expressed as the following: In mathematical terms, pressure can be expressed as the following: SI accepted it as the standard unit of pressure in 1971 and named it after Blaise Pascal. Specifically, a pascal measures the pressure applied by 1 N of force applied on an area of 1 m 2 at a right angle. In the meter-kilogram-second system, it is expressed in pascals. Pressure is the force applied over an area. For most engineering problems, the unit is too small to properly represent pressure or stress, which is why it is often expressed in its multiples, like the kilopascal (kPa), megapascal (MPa), millibar (100 Pa), etc. The pascal is also used to measure stress, specifically tectonic stress in the Earth's plates. One pascal is equivalent to 1 newton (N) of force applied over an area of 1 square meter ( m 2). It is named after the scientist and mathematician Blaise Pascal. Today we have separated these cleanly into forces, momenta, accelerations, inertia, kinetic energy, potential energy, etc.The pascal (Pa) is the unit of pressure or stress in the International System of Units ( SI). As a side note, the development of mechanics was muddled at first because people used the word "force" and similar words for a whole variety of related concepts without appreciating the differences. It all depends on where you take your starting place to be. If you look at the units of force $\mathrm$, and this would serve as a definition of the kilogram. Remember that momentum is a vector and a change in a vector can involve a change in magnitude, a change in direction, or both (any arbitrary change in a vector can be decomposed into a change in magnitude parallel or antiparallel to the vector and a change in direction perpendicular to the vector). If a force acts on that particle, its momentum will change. It moves through space with constant momentum. There's indeed an underlying intuition with units. This is precisely the type of question I've started asking my introductory students.
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