Units & Prefixes (Edexcel GCSE Physics: Combined Science)

• There are a seemingly endless number of units in Physics
  • These can all be reduced to six base units from which every other unit can be derived

• These seven units are referred to as the SI Base Units; this is the only system of measurement that is officially used in almost every country around the world

SI Base Quantities Table

• These base units are then used to derive other common units
• These units have special names, for example:
  • Newtons, N [kg m / s²]
  • Joules, J [N m]
  • Pascals, Pa [kg / m s²]

Common Units Table

Prefixes Table

Example Conversions

• 12 GPa = 12 gigapascals = 12 × 10⁹ Pa (12 000 000 000 Pa)
• 5 kN = 5 kilonewtons = 5 × 10³ N (5000 N)
• 0.1 μA = 0.1 microamps = 1 × 10^–7 A (0.0000001 A)
• 7 nC = 7 nanocoulombs = 7 × 10^–9 C (0.000000007 C)