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  2. List of international units - Wikipedia

    en.wikipedia.org/wiki/List_of_international_units

    Unit system Domain Derivation Unit name Unit symbol Dimension symbol Quantity name Definition In SI base units In other SI units SI: Physics: Basic: second [n 1] s: T: time: The duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium-133 atom. s: SI ...

  3. International System of Units - Wikipedia

    en.wikipedia.org/wiki/International_System_of_Units

    The International System of Units, internationally known by the abbreviation SI (from French Système international d'unités), is the modern form of the metric system and the world's most widely used system of measurement. It is the only system of measurement with official status in nearly every country in the world, employed in science ...

  4. Unit of time - Wikipedia

    en.wikipedia.org/wiki/Unit_of_time

    The TU (for time unit) is a unit of time defined as 1024 μs for use in engineering. The svedberg is a time unit used for sedimentation rates (usually of proteins). It is defined as 10 −13 seconds (100 fs). The galactic year, based on the rotation of the galaxy and usually measured in million years. [2]

  5. Newton (unit) - Wikipedia

    en.wikipedia.org/wiki/Newton_(unit)

    The newton (symbol: N) is the unit of force in the International System of Units (SI). Expressed in terms of SI base units, it is 1 kg⋅m/s 2, the force that accelerates a mass of one kilogram at one metre per second squared. The unit is named after Isaac Newton in recognition of his work on classical mechanics, specifically his second law of ...

  6. List of physical quantities - Wikipedia

    en.wikipedia.org/wiki/List_of_physical_quantities

    Energy per unit temperature change J/K L 2 M T −2 Θ −1: extensive Heat flux density: ϕ Q: Heat flow per unit time per unit surface area W/m 2: M T −3: Illuminance: E v: Wavelength-weighted luminous flux per unit surface area lux (lx = cd⋅sr/m 2) L −2 J: Impedance: Z: Resistance to an alternating current of a given frequency ...

  7. SI base unit - Wikipedia

    en.wikipedia.org/wiki/SI_base_unit

    "The kelvin, symbol K, is the SI unit of thermodynamic temperature. It is defined by taking the fixed numerical value of the Boltzmann constant k to be 1.380 649 × 10 −23 when expressed in the unit J K −1, which is equal to kg m 2 s −2 K −1, where the kilogram, metre and second are defined in terms of h, c and ∆ν Cs." [1]

  8. Matter - Wikipedia

    en.wikipedia.org/wiki/Matter

    Exotic matter is a concept of particle physics, which may include dark matter and dark energy but goes further to include any hypothetical material that violates one or more of the properties of known forms of matter.

  9. List of physical constants - Wikipedia

    en.wikipedia.org/wiki/List_of_physical_constants

    The constants listed here are known values of physical constants expressed in SI units; that is, physical quantities that are generally believed to be universal in nature and thus are independent of the unit system in which they are measured. Many of these are redundant, in the sense that they obey a known relationship with other physical ...