Physical quantities, units and measurement
SI quantities, prefixes, scale, instrument choice, scalars and vectors.
Learning goals
- Represent a physical quantity with a numerical magnitude and unit
- Recall the six prescribed SI base quantities and their units
- Use the prescribed SI prefixes from nano to tera
- Compare orders of magnitude from a typical atom to the Earth
- Select and justify measuring instruments by range and precision
- Distinguish scalar and vector quantities and give examples
G2 Science (Physics) · Topic 1
Read the complete lesson from top to bottom first. Pause for its examples and independent questions, then use a short topic check to decide what to practise again.
Build the idea in order
- Quantities and units
- Scale and prefixes
- Suitable instruments
- Scalars and vectors
Lessons
Physical quantities, units and measurement
Use SI quantities and prefixes, choose measuring instruments, compare scale, and distinguish scalar from vector quantities.
Check your understanding
Physical quantities, units and measurement topic check
Check the required topic capabilities and get focused practice for ideas that need another look.
G2 Science Structured Practice — Measurement, Force and Pressure
Marked practice for G2 Science measurement and pressure: unit and area conversions, reading scales, choosing instruments, density and contact pressure.
What to remember
- Write every measured quantity as a numerical magnitude with a unit.
- Recall the six base units: kilogram, metre, second, ampere, kelvin and mole.
- Apply a prefix factor to the whole unit and square it for area conversions.
- Choose an instrument by both range and resolution.
- A vector has direction as well as magnitude and unit; a scalar does not.
Topic and syllabus information
Physical quantities, units and measurement is Topic 1 in K223 / K224 Physics component · 2027.
The lesson stays within G2 depth and includes the explanations, examples and practice needed for this topic.
Reviewed 9 Aug 2026
Continue with the next resource in this course.
Course and syllabus information
- Course
- SEC G2 Science Physics component
- Edition
- SEC G2 Science Physics component 2027