Compound measures
Speed, density, pressure: rate of one quantity per unit of another.
Compound measures: speed (distance/time), density (mass/volume), pressure (force/area). Each obeys the same triangle rearrangement.
Worked examples
120 miles in 2 h = 60 mph.
500 g of water = 500 cm³ (density 1).
Pressure = force/area: 100 N on 0.5 m² = 200 Pa.
Frequently asked questions
Unit conversions?
30 m/s = 108 km/h (multiply by 3.6). g/cm³ <-> kg/m³ ×1000.
Why ‘compound’?
It combines two simple measures (mass + volume → density, etc.).