This key facts covers The Three Essential Compound Measures within Compound Measures for GCSE Mathematics. Revise Compound Measures in Number for GCSE Mathematics with 12 exam-style questions and 22 flashcards. This topic appears regularly enough that it should still be part of a steady revision cycle. It is section 2 of 8 in this topic. Use this key facts to connect the idea to the wider topic before moving on to questions and flashcards.
The Three Essential Compound Measures
| Compound Measure | Components | Formula | Units |
|---|---|---|---|
| Speed | Distance ÷ Time | S = D/T | m/s, mph, km/h |
| Density | Mass ÷ Volume | D = M/V | g/cm³, kg/m³ |
| Pressure | Force ÷ Area | P = F/A | N/m², Pa (Pascals) |
Practice questions for Compound Measures
Which formula correctly gives speed in terms of distance and time?
A car travels 80 km at 40 km/h and then 80 km at 80 km/h. Explain why the average speed for the whole journey is NOT 60 km/h.
Quick recall flashcards
Convert 72 km/h to m/s
Divide by 3.6
72 ÷ 3.6 = 20 m/s
Check: 72 km/h means 72000 m per 3600 s
72000 ÷ 3600 = 20 m/s
Convert 25 m/s to km/h
Multiply by 3.6
25 × 3.6 = 90 km/h
Check: 25 m/s means 25 metres per second
25 × 3600 ÷ 1000 = 90 km/h