Physical Quantities
Quantity | Definition | Formula | Units | Dimensions | |
---|---|---|---|---|---|
Length or Distance | fundamental | d | m (meter) | L (Length) | |
Time | fundamental | t | s (second) | T (Time) | |
Mass | fundamental | m | kg (kilogram) | M (Mass) | |
Area | distance^{2} | A = d^{2} | m^{2} | L^{2} | |
Volume | distance^{3} | V = d^{3} | m^{3} | L^{3} | |
Density | mass / volume | d = m/V | kg/m^{3} | M/L^{3} | |
Velocity | distance / time | v = d/t | m/s c (speed of light) |
L/T | |
Acceleration | velocity / time | a = v/t | m/s^{2} | L/T^{2} | |
Momentum | mass × velocity | p = m·v | kg·m/s | ML/T | |
Force Weight |
mass × acceleration mass × acceleration of gravity |
F = m·a W = m·g |
N (newton) = kg·m/s^{2} | ML/T^{2} | |
Pressure or Stress | force / area | p = F/A | Pa (pascal) = N/m^{2} = kg/(m·s^{2}) | M/LT^{2} | |
Energy or Work Kinetic Energy Potential Energy |
force × distance mass × velocity^{2} / 2 mass × acceleration of gravity × height |
E = F·d KE = m·v^{2}/2 PE = m·g·h |
J (joule) = N·m = kg·m^{2}/s^{2} | ML^{2}/T^{2} | |
Power | energy / time | P = E/t | W (watt) = J/s = kg·m^{2}/s^{3} | ML^{2}/T^{3} | |
Impulse | force × time | I = F·t | N·s = kg·m/s | ML/T | |
Action | energy × time momentum × distance |
S = E·t S = p·d |
J·s = kg·m^{2}/s h (quantum of action) |
ML^{2}/T | |
Angle | fundamental | θ | ° (degree), rad (radian), rev 360° = 2π rad = 1 rev |
dimensionless | |
Cycles | fundamental | n | cyc (cycles) | dimensionless | |
Frequency | cycles / time | f = n/t | Hz (hertz) = cyc/s = 1/s | 1/T | |
Angular Velocity | angle / time | ω = θ/t | rad/s = 1/s | 1/T | |
Angular Acceleration | angular velocity / time | α = ω/t | rad/s^{2} = 1/s^{2} | 1/T^{2} | |
Moment of Inertia | mass × radius^{2} | I = m·r^{2} | kg·m^{2} | ML^{2} | |
Angular Momentum | radius × momentum moment of inertia × angular velocity |
L = r·p L = I·ω |
J·s = kg·m^{2}/s ћ (quantum of angular momentum) |
ML^{2}/T | |
Torque or Moment | radius × force moment of inertia × angular acceleration |
τ = r·F τ = I·α |
N·m = kg·m^{2}/s^{2} | ML^{2}/T^{2} | |
Temperature | fundamental | T | °C (celsius), K (kelvin) | K (Temp.) | |
Heat | heat energy | Q | J (joule) = kg·m^{2}/s^{2} | ML^{2}/T^{2} | |
Entropy | heat / temperature | S = Q/T | J/K | ML^{2}/T^{2}K | |
Electric Charge +/- | fundamental | q | C (coulomb) e (elementary charge) |
Q (Charge) | |
Current | charge / time | i = q/t | A (amp) = C/s | Q/T | |
Voltage or Potential | energy / charge | V = E/q | V (volt) = J/C | ML^{2}/QT^{2} | |
Resistance | voltage / current | R = V/i | Ω (ohm) = V/A | ML^{2}/Q^{2}T | |
Capacitance | charge / voltage | C = q/V | F (farad) = C/V | Q^{2}T^{2}/ML^{2} | |
Inductance | voltage / (current / time) | L = V/(i/t) | H (henry) = V·s/A | ML^{2}/Q^{2} | |
Electric Field | voltage / distance force / charge |
E = V/d E = F/q |
V/m = N/C | ML/QT^{2} | |
Electric Flux | electric field × area | Φ_{E} = E·A | V·m = N·m^{2}/C | ML^{3}/QT^{2} | |
Magnetic Field | force / (charge × velocity) | B = F/(q·v) | T (tesla) = Wb/m^{2} = N·s/(C·m) | M/QT | |
Magnetic Flux | magnetic field × area | Φ_{M} = B·A | Wb (weber) = V·s = J·s/C | ML^{2}/QT |
Note: Other conventions define different quantities to be fundamental.
Mass, energy, momentum, angular momentum, and charge are conserved, which means the total amount does not change in an isolated system.