1. Quantities and Units
Let's start A Level Physics with a look at the quantities we measure and the units they are measured in.
2. Base Units
There are just 7 base units from which we can make all the others. These are all precisely defined so that 1 kg is always equal to 1 kg.
3. Derived Units
Newtons, joules and even the volt can all be made up from combinations of the 7 base units. This video shows how.
4. Unit Prefixes
Because Physics is about absolutely everything in the Universe we have to cover both the extremely large and also the incredibly small. Rather than writing numbers like 100000000 or 0.0000000000001 we can use prefixes from the GIGAlarge to the femtosmall.