Quantities, units and symbols

It is most important that when you write down a quantity you give it the correct units and use the correct symbol for those units. The following table shows most of the common quantities.

Quantity measured	Name of unit	Symbol for unit
Length (L)	metre	m
Mass (m)	kilogram	kg
Time (t)	second	s
Velocity (speed) (v)	metres per second	m/s
Acceleration (a)	metres per second per second	m/s2
Momentum	Newton seconds	Ns
Force (F)	Newton	N
Energy	joule	J
Work	joule	J
Power (P)	watt	W
Density (ρ)	kilograms per metre cubed	kg/m3
Pressure	Pascal, Newtons per metre squared	Pa, N/m2
Frequency (f)	Hertz	Hz
Temperature	degrees centigrade, Kelvin	oC, K
Specific heat capacity	Joules per kilogram per degree C	J/kgoC
Specific latent heat	joules per kilogram	J/kg
Charge (Q)	coulomb	C
Current (I)	ampere (amp)	A
Voltage (V)	volt	V
Potential difference	volt	V
Resistance (R)	ohm	Ω