Units of MeasureSection 1.2 Metric Length

Pre-View 1.2

• Meter – the standard SI unit for measuring length.

• Ruler or meter stick – tool used to measure length in centimeters or millimeters

• The smallest marks on a ruler or meter stick indicate millimeters (mm).

• There are 1000 mm in one meter.• The longer marks on a ruler or meter stick

show centimeters (cm) – 10 mm = 1 cm, and there are 100 cm in one meter.

• Longer lengths are measured in kilometers (km), which are 1000 meters.

10 mmor

1 cm

SI unit of Length: Kilometer (km)

• When to use it…–Use kilometers for long distances.

• Example:–The distance from Birmingham to

Anniston is about 106 km

SI unit of Length: Meter (m)

• When to use it…–Use meters instead of feet or yards.

• Example:–The height of an average room from

floor to ceiling is about 3 m

SI unit of Length: Centimeter (cm)

• When to use it…–Use centimeters instead of inches.

• Example:–One inch is 2.54 cm. The width of

notebook paper is about 21.6 cm

SI unit of Length: Millimeter (mm)

• When to use it…–Use millimeters for small but visible

lengths.

• Example:–The diameter of an average pencil is

7 mm

SI unit of Length: Micrometer (μm)

• When to use it…–Use micrometers to measure very small

or microscopic dimensions.

• Example:–The length of a paramecium is about

50 μm