Foundations of Physics — 63 Terms Defined

Absolute Uncertainty Foundations of Physics Various The margin of measurement error expressed in the same physical units as the quantity being measured. x = x_mean ± Δx

Absolute Zero Foundations of Physics K The theoretical lower limit of thermodynamic temperature, defined as 0 Kelvin (-273.15°C or -459.67°F). 0 K = -273.15°C

Accuracy Foundations of Physics % The degree of closeness of a measured value or experimental result to the true or accepted reference value. Error = |Measured - True| / True × 100%

Ampere Foundations of Physics A The SI base unit of electric current, defined by fixing the elementary charge to e = 1.602176634 × 10⁻¹⁹ C. 1 A = 1 C / s

Avogadro's Number Foundations of Physics mol⁻¹ The exact number of elementary entities (atoms, molecules, ions) contained in one mole of a substance. Na = 6.02214076 × 10²³ mol⁻¹

Base Units Foundations of Physics The 7 SI Base Units The set of seven mutually independent fundamental units of measurement defined by the International System of Units.

Boltzmann Constant Foundations of Physics J/K The fundamental constant that converts thermodynamic temperature into microstate kinetic energy per particle. k = R / Na = 1.380649 × 10⁻²³ J/K

Candela Foundations of Physics cd The SI base unit of luminous intensity in a given direction, defined by fixing the luminous efficacy of 540 THz monochromatic radiation to 683 lm/W. Iv = dΦv / dΩ

Cartesian Coordinates Foundations of Physics m An orthogonal coordinate system that specifies point locations in space using signed distance projections along mutually perpendicular axes (x, y, z). d = √((x2-x1)² + (y2-y1)² + (z2-z1)²)

Centre of Mass Foundations of Physics m The unique spatial point representing the mean mass-weighted position of a physical system or extended rigid body. R_cm = ∑ m_i r_i / ∑ m_i

Combining Uncertainties Foundations of Physics Various The mathematical rules used to propagate individual measurement uncertainties into calculated final results. Addition: ΔZ = √(ΔX² + ΔY²); Product: ΔZ/Z = √((ΔX/X)² + (ΔY/Y)²)

Control Variable Foundations of Physics Various Any experimental parameter held strictly constant throughout an investigation to isolate the relationship between independent and dependent variables.

Cylindrical Coordinates Foundations of Physics m, rad, m A 3D coordinate system combining 2D polar coordinates (r, θ) in the transverse plane with a linear vertical height axis z. x = r cos θ, y = r sin θ, z = z

Density Foundations of Physics kg/m³ The mass per unit volume of a substance under specified temperature and pressure conditions. ρ = m / V

Dependent Variable Foundations of Physics Various The factor measured or observed in an experiment that changes in response to manipulations of the independent variable.

Derived Units Foundations of Physics Various Units of measurement formed as algebraic combinations of the seven fundamental SI base units.

Dimensional Analysis Foundations of Physics Dimensionless An analytical method used to verify equation consistency and establish mathematical relationships between physical quantities by examining fundamental dimensions. [M]^a [L]^b [T]^c

Elementary Charge Foundations of Physics C The fundamental electric charge carried by a single proton, or the absolute value of charge carried by a single electron. e = 1.602176634 × 10⁻¹⁹ C

Energy Foundations of Physics J The quantitative property that must be transferred to a physical system to perform work on it, or to heat it. E = mc²

Frame of Reference Foundations of Physics N/A A coordinate system along with a clock used to record positions, velocities, and times of physical events.

Fundamental Constants Foundations of Physics Various Universal physical quantities whose numerical values are constant in space and time throughout the cosmos.

Gravitational Constant Foundations of Physics N·m²/kg² The empirical physical constant relating the gravitational force between two masses to their product and inverse-square separation. G = 6.67430 × 10⁻¹¹ N·m²/kg²

Gravitational Mass Foundations of Physics kg A measure of the strength of the gravitational force exerted or experienced by an object in a gravitational field. m = F_g / g

Hypothesis Foundations of Physics N/A A proposed, testable explanation for an observed physical phenomenon, serving as the starting point for experimental investigation.