Space & Time symbol quantity symbol SI unit r, r position, separation, radius, radius of curvature m meter s, s displacement, distance m meter θ, φ, θ, φ angle, angular displacement, angular separation, rotation angle rad radian x, y, z cartesian coordinates m meter î, ĵ, k̂ cartesian unit vectors unitless r, θ, φ spherical coordinates m, rad meter, radian r̂, θ̂, φ̂ spherical unit vectors unitless ρ, φ, z cylindrical coordinates m, rad meter, radian ρ̂, φ̂, ẑ cylindrical unit vectors unitless n̂ normal unit vector unitless t̂ tangential unit vector unitless h height, depth m meter ℓ, L length m meter d distance, separation, thickness m meter t thickness m meter D diameter m meter C circumference m meter A, A area, cross-sectional area, projected area, surface area m2 square meter V volume m3 cubic meter t time, duration s second T period, periodic time s second τ time constant s second f frequency Hz hertz ω angular frequency rad/s radian per second Mechanics symbol quantity symbol SI unit v, v velocity, speed m/s meter per second a, a acceleration m/s2 meter per second squared ac, ac centripetal acceleration, centrifugal acceleration m/s2 meter per second squared g, g gravitational field, acceleration due to gravity m/s2 meter per second squared m mass kg kilogram F, F force N newton Fg, W, W force of gravity, weight N newton Fn, N, N normal force, normal N newton Ff, fs, fk force of friction (static, kinetic) N newton μs, μk coefficient of friction (static, kinetic) unitless p, p momentum kg m/s kilogram meter per second J, J impulse N s newton second W work J joule E energy, total energy J joule K, Kt, Kr kinetic energy (translational, rotational) J joule U, Ug, Us potential energy (gravitational, spring) J joule Vg gravitational potential J/kg joule per kilogram η efficiency unitless P power W watt ω, ω rotational velocity, rotational speed rad/s radian per second α, α rotational acceleration rad/s2 radian per second squared τ, τ torque N m newton meter I moment of inertia kg m2 kilogram meter squared L, L angular momentum kg m2/s kilogram meter squared per second H, H angular impulse N m s newton meter second k spring constant N/m newton per meter P pressure Pa pascal σ normal stress Pa pascal τ shear stress Pa pascal ρ density, volume mass density kg/m3 kilogram per cubic meter σ area mass density, superficial mass density kg/m2 kilogram per square meter λ linear mass density kg/m kilogram per meter FB, B, B buoyancy, buoyant force N newton qm mass flow rate kg/s kilogram per second qV volume flow rate m3/s cubic meter per second FD, R, R drag, aerodynamic drag, air resistance N newton C, CD drag coefficient, coefficient of drag unitless η viscosity, dynamic viscosity Pa s pascal second ν kinematic viscosity m2/s square meter per second Ma mach number unitless Re reynolds number unitless Fr froude number unitless E young's modulus, modulus of elasticity Pa pascal G shear modulus, modulus of rigidity Pa pascal K bulk modulus, modulus of compression Pa pascal ε linear strain unitless γ shear strain unitless θ volume strain unitless γ surface tension N/m newton per meter Thermal Physics symbol quantity symbol SI unit T temperature K kelvin α linear expansivity, coefficient of linear thermal expansion K−1 inverse kelvin β volume expansivity, coefficient of volume thermal expansion K−1 inverse kelvin Q heat J joule c specific heat, specific heat capacity J/kg K joule per kilogram kelvin L latent heat, specific latent heat J/kg joule per kilogram n amount of substance mole N number of particles unitless P heat flow rate W watt k thermal conductivity W/m K watt per meter kelvin ε emissivity unitless U internal energy J joule S entropy J/K joule per kelvin w ways, number of identical microstates unitless COP coefficient of performance unitless Waves & Optics symbol quantity symbol SI unit λ wavelength m meter v, c wave speed m/s meter per second I intensity W/m2 watt per square meter L level dB, dNp decibel, decineper n index of refraction, absolute index of refraction unitless f focal length m meter M magnification unitless Electricity & Magnetism symbol quantity symbol SI unit q, Q charge, electric charge C coulomb ρ charge density, volume charge density C/m3 coulomb per cubic meter σ area charge density, superficial charge density C/m2 coulomb per square meter λ linear charge density C/m coulomb per meter FE, FE electric force, electrostatic force N newton E, E electric field N/C, V/m newton per coulomb, volt per meter ΦE electric flux N m2/C, V m newton meter squared per coulomb, volt meter U, UE potential energy, electric potential energy J joule V, VE voltage, potential, electric potential V volt ℰ electromotive force, emf V volt C capacitance F farad κ dielectric constant unitless I current, electric current A ampère R, r resistance, electrical resistance, internal resistance Ω ohm ρ resistivity Ω m ohm meter G conductance S siemens σ conductivity S/m siemens per meter FB, FB magnetic force N newton B, B magnetic field T tesla ΦB magnetic flux Wb weber N number of turns unitless n turns per unit length, turns density m−1 inverse meter η energy density J/m3 joule per cubic meter S, S poynting vector, intensity W/m2 watt per square meter Modern Physics symbol quantity symbol SI unit γ lorentz factor, lorentz gamma unitless φ work function J joule ψ(r,t), ψ(r)φ(t) wave function unitless T½ half life s second D dose, absorbed dose Gy gray H effective dose Sv sievert miscellaneous symbols Mathematical symbols and notation symbol description + plus, add, positive − minus, subtract, negative ± uncertainty, error, plus-minus · multiply, dot, dot product, scalar product × multiply, cross, cross product, vector product ÷, / divide x2 square x3 cube √ square root, root, radical ∛ cube root 1 x , x−1 invert, reciprocal = equal to, equality ≈ approximately equal to ∝ proportional to ≠ not equal to, inequality ~ on the order of, tilde < less than > greater than ≤ less than or equal to ≥ greater than or equal to ⇒, ⇐ logical implication ⇔ logical equivalence … and so on, ellipsis ∴ therefore f(x) function sin sine cos cosine tan tangent sinh hyperbolic sine cosh hyperbolic cosine tanh hyperbolic tangent x̂ unit vector, hat, circumflex ∥ parallel ⟂ perpendicular x mean, average, antiparticle, bar, overline x̃ median, supersymetric particle, tilde ⟨⟩ time average, ensemble average, bracket p(x) probability distribution, probability density function ∆ increment, change, delta d differential, d ∂ partial differential, d partial ∇ gradient, del ∇· divergence, div, del dot ∇× curl, del cross ∇2 laplacian, del squared ∑ summation, sigma ∫ integral ∬ double integral ∭ triple integral ∮ contour integral ∯ surface integral ∰ volume integral ∞ infinity ℵ0 transfinite number, aleph null Greek alphabet (with variants) letter English name letter English name Α, α alpha Ν, ν nu Β, β, ϐ beta Ξ, ξ xi Γ, γ gamma Ο, ο omicron Δ, ∆, δ delta Π, ∏, π, ϖ pi Ε, ε, ϵ epsilon Ρ, ρ, ϱ rho Ζ, ζ zeta Σ, ∑, σ, ς sigma Η, η eta Τ, τ tau Θ, ϴ, θ, ϑ theta Υ, υ upsilon Ι, ι iota Φ, φ, ϕ phi Κ, κ, ϰ kappa Χ, χ chi Λ, λ lambda Ψ, ψ psi Μ, μ, µ mu Ω, Ω, ω omega