Converting units of speed, density and pressure

Speed, density and pressure are examples of compound measures which means they are made up of two or more other measures. For example, speed is made up of distance and time.

To convert the units of compound measures, convert the individual units separately.

Example

The maximum speed of a racing car is 340 km/h. Convert this speed into m/s (give the answer to one decimal place).

First convert kilometres into metres.

1 km = 1,000 m

Next convert hours into seconds.

1 h = 3,600 s

Finally combine the two unit conversions.

\(340~\frac{\text{km}}{\text{h}} = \frac{340 \times 1,000}{3,600}~\frac{\text{m}}{\text{s}}\)

\(340 \times 1,000 \div 3,600 = 94.4~\text{m/s}\)

Question

The density of gold is 19.3 g/cm³. Convert this into kg/m³.

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Test your understanding

Converting units of volume

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Units of measure - EdexcelConverting units of speed, density and pressure