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Compound MeasuresEdexcel GCSE Maths: Flashcards

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What is a compound measure?

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What is a compound measure?
A measure made by dividing one quantity by another, combining two units into a single rate.
What are the three compound measures you need for GCSE?
Speed, density and pressure.
What is the formula for speed?
speed = distance ÷ time.
What is the formula for density?
density = mass ÷ volume.
What is the formula for pressure?
pressure = force ÷ area.
A car travels 150 km in 3 hours. What is its speed?
50 km/h (150 ÷ 3).
An object has mass 45 g and volume 9 cm³. What is its density?
5 g/cm³ (45 ÷ 9).
How do you find mass if you know density and volume?
mass = density × volume.
Why must units match before calculating a compound measure?
Because mixing units (e.g. km with minutes) gives an incorrect result — convert first.
5 kg of apples costs £4.50. What is the unit price?
£0.90 per kg (4.50 ÷ 5).
How do you fairly compare two different special offers?
Convert both to the same unit rate (e.g. price per kg) before comparing.
A metal cube has side 2 cm and density 8 g/cm³. Find its mass.
Volume = 2³ = 8 cm³; mass = 8 × 8 = 64 g.