Contents
Key Stage 4
Meaning
SI Units are the standard scientific units used by scientists around the world.
About SI Units
- SI stands for "Système international".
- SI units have been standardised around the world so that any experiment can be reproduced and so that components in machines are interchangeable.
- The USA does not always use SI Units. As a result of the confusion over units a space probe once crashed on Mars because one team of scientists was using inches and the other team was using hundredths of metre (centimetres) and a mistake was made converting from one to the other.
The SI Units you should know are in the following table:
Measurement | SI Unit |
Distance, Displacement, Wavelength | metres |
Time | seconds |
Temperature | degrees Celsius or Kelvin |
Mass | kilograms |
Area | metres squared |
Volume | metres cubed |
Force, Weight | Newtons |
Speed and Velocity | metres per second |
Density | kilograms per metre cubed |
Angle | degrees |
Acceleration | metres per second per second |
Moment | Newton Metres |
Energy, Work Done | Joules |
Electrical Charge | Coulombs |
Electrical Current | Amps |
Potential Difference | Volts |
Resistance | Ohms |
Radioactivity | Becquerels |
Radiation Dose | Ohms |
Frequency | Hertz |
Magnetic Flux Density | Teslas |
Moles | Mol |
Concentration | Mol per decimeter cubed |
Light intensity | Lux |