MEASUREMENTS

Chapter 13: Physics

Measuring lengthThe standard SI unit for measuring length is metre. Unit Symbol Number of

metersKilometre km 1000 mMetre m 1 mCentimetre cm 0.01 mMillimetre mm 0.001 mMicrometre μm 0.000 001 mnanometre nm 0.000 000 001

m

Measuring MassThe standard SI unit for measuring mass is kilogram. Unit Symbol Number of

kilogramsmegaton Mt 1000 000 000

kgton t 1000 kgKilogram kg 1 kgGram g 0.001 kgmilligram mg 0.000 001 kg

Balance scales

Top pan balance

Spring balance

Measuring timeThe standard SI unit for measuring time is the second. Unit Symbol Number of

kilogramsDay d 86 400 s (1440

min. or 24 h)Hour h 3600 s (60

min.)Minute min 60 sSecond s 1 smillisecond ms 0.001 s

Measuring Temperature The hotness or coldness of a

substance is measured by taking its temperature.

The temperature of a substance is measured on a scale.

The most commonly used temperature scale is the Celsius scale.

Its two fixed points are 0 ⁰C and 100 ⁰C.

Laboratory thermometers usually have a scale from -10 ⁰C to 110 ⁰C.

The lowest possible temperature, known as absolute zero is -273 ⁰C.

Temperatures can go as high as millions of degrees Celsius.

Liquids in thermometers Two liquids that are commonly used in

thermometers are mercury and alcohol.

Mercury has a freezing point of -39 ⁰C and a boiling point of 360 ⁰C.

Alcohol has a freezing point of -112 ⁰C and a boiling point of 78 ⁰C.