Unit 1.1.1 - Uses of SI Units

• Base SI units: standard quantities used to measure in physics
• SI units: the international system of units
• There are seven base SI units
• Ampere (A) is the measure of electric current
• Candela (cd) is the measure of luminous intensity
• Kilogram (kg) is the measure of mass
• Second (s) is the measure of time
• Metre (m) is the measure of time
• Kelvin (K) is the measure of temperature
• Mole (mol) is the measure of chemical mass
• SI units can be combined to form other, more useful, SI units
• Celsius is the measure of temperature, derived from the base SI unit Kelvin (K)
• Coulomb (C) is the measure of electrical current
• Hertz (Hz) is the measure of frequency
• Joules (J) are a measure of energy
• Newton (N) is a measure of force
• Ohm (Ω) is a measure of electrical resistance
• Pascal (Pa) is the measure of pressure
• Tesla (T) is the measure of magnetic flux density
• Volt (V) is the measure of electrical potential difference
• Watt (W) is the measure of power
• What is the formula for converting kelvin to celsius?

  C = K - 273
• The seven base SI units are candela, kilograms, metres, kelvin, amperes, seconds, and moles
• The spring constant SI units are Nm$^-1$ but the base SI units are kgs$^-2$
• The SI units of pressure are Pa or N/m$^2$ but the base SI units are $kgm^-1s^-2$
• The SI units of energy are J but the base SI units are $kgm^2s^-2$
• The SI unit of voltage is V but the base SI units are $kgm^2A^-1s^-3$