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Symbol Name Meaning SI unit of measure alpha: alpha particle: angular acceleration: radian per second squared (rad/s 2) fine-structure constant: unitless beta: velocity in terms of the speed of light c: unitless beta particle: gamma: Lorentz factor: unitless photon: gamma ray: shear strain: radian
In physics and engineering, mass flux is the rate of mass flow per unit of area. Its SI units are kg ⋅ s −1 ⋅ m −2. The common symbols are j, J, q, Q, φ, or Φ (Greek lowercase or capital Phi), sometimes with subscript m to indicate mass is the flowing quantity. This flux quantity is also known simply as "mass flow". [1] "
(Common) symbol/s Defining equation SI unit Dimension Wavefunction: ψ, Ψ To solve from the Schrödinger equation: varies with situation and number of particles Wavefunction probability density: ρ = | | = m −3 [L] −3: Wavefunction probability current: j: Non-relativistic, no external field:
Quantity (common name/s) (Common) symbol/s SI units Dimension Number of wave cycles N: dimensionless dimensionless (Oscillatory) displacement Symbol of any quantity which varies periodically, such as h, x, y (mechanical waves), x, s, η (longitudinal waves) I, V, E, B, H, D (electromagnetism), u, U (luminal waves), ψ, Ψ, Φ (quantum mechanics).
Mass of a substance as a fraction of the total mass kg/kg 1: intensive (Mass) Density (or volume density) ρ: Mass per unit volume kg/m 3: L −3 M: intensive Mean lifetime: τ: Average time for a particle of a substance to decay s T: intensive Molar concentration: C: Amount of substance per unit volume mol⋅m −3: L −3 N: intensive Molar ...
Continuous charge distribution. The volume charge density ρ is the amount of charge per unit volume (cube), surface charge density σ is amount per unit surface area (circle) with outward unit normal nĚ‚, d is the dipole moment between two point charges, the volume density of these is the polarization density P.
The equation for the mass shell is also often written in terms of the four-momentum; in Einstein notation with metric signature (+,−,−,−) and units where the speed of light =, as =. In the literature, one may also encounter p μ p μ = − m 0 2 {\displaystyle p^{\mu }p_{\mu }=-m_{0}^{2}} if the metric signature used is (−,+,+,+).
n (no standard symbol) = / / dimensionless dimensionless Radioisotope time constant, mean lifetime of an atom before decay τ (no standard symbol) = / s [T] Absorbed dose, total ionizing dose (total energy of radiation transferred to unit mass) D can only be found experimentally