Base Units

Kilogram

Base SI unit for measuring mass Defined as the mass of a specific platinum-iridium alloy in France Symbol: kg

Metre

Base SI unit for measuring length Defined as the distance travelled by light in 1/299792458 seconds Symbol: m

Second

Base SI unit for measuring time Defined as exactly 9,192,631770 cycles of a Caesium atomic rock Symbol: s

Ampere

Base SI unit for measuring current Defined as the current which if put through two parallel metre-long conductors places one metre apart in a vacuum, the force between them would be equal to 2 x 10^ -7 N Symbol: A (Amps)

Mole

Base SI unit for measuring the amount of a substance Defined as the amount of a substance which contains the same number of particles as atoms in 12 grams of carbon-12 Symbol: mol

Kelvin

Base SI unit for measuring temperature The Kelvin scale is defined so the the triple point of water is at 273.6K; this is the temperature and pressure at which water exists as a gas, liquid, and solid together in thermodynamic equilibrium Symbol: K

Coulomb

Unit for measuring charge Derived from the ampere and the second (1 coulomb is 1 ampere-second) Symbol: C (As)

Newton

Unit for measuring force Derived from the kilogram, metre, and second (1 Newton is the force applied to a 1kg mass to cause it to accelerate at 1 metre per second squared) Symbol: N (kgms^ -2)