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Quantities and units
Express physical quantities in consistent units. Check that both sides of an equation describe the same kind of quantity before substituting values.
Specification outcomes (8)
- 2.1.1(a) Physical quantities have a numerical value and a unit.
- 2.1.1(b) Make estimates of physical quantities listed in the specification.
- 2.1.2(a) Système Internationale (S.I.) base quantities and their units – mass (kg), length (m), time (s), current (A), temperature (K), amount of substance (mol).
- 2.1.2(b) Derived units of S.I. base units, such as momentum (kg m s⁻¹) and density (kg m⁻³).
- 2.1.2(c) Recognise and use units listed in this specification.
- 2.1.2(d) Check the homogeneity of physical equations using S.I. base units.
- 2.1.2(e) Use prefixes and their symbols to indicate decimal submultiples or multiples of units (pico, nano, micro, milli, centi, deci, kilo, mega, giga, tera).
- 2.1.2(f) Apply conventions for labelling graph axes and table columns, for example speed / m s⁻¹.
H156 v2.0 · May 2026
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