Prefixes in the SI Multiples Submultiples Factor Prefix Factor Prefix 1018 exa E 10-18 atto a 1015 peta P 10-15 femto f 1012 tera T 10-12 pico p 109 giga G 10-9 nano n 106 mega M 10-6 micro n 103 kilo k 10-3 milli m 102 hecto h 10-2 centi c 10 deca da 10-1 deci d Science of ten dea ls w ith ver y la rge or ver y sma l l numbers. Mu ltiples and submu ltiples of the un its a re used for these amounts. The SI def ines the pref i xes for these numbers. For example: • The size of some cel ls is 0.0 0 0 0 03 m, or 3 µm. • The d istance f rom the Ea r th to the Sun is 149 597 870 70 0 m, or 149.6 Gm. The SI a lso ex pla ins how to w r ite numbers and units. Derived quantities in the SI Name Symbol Unit Other accepted units Area A m2 ha (hectare); 1 ha = 10 000 m2 Volume V m3 L (litre); 1 L = 1 dm3; 1 m3 = 1 000 L Density d, t kg/m3 g/L = kg/m3 ; kg/L ; 1 kg/L = 1 000 kg/m3 Speed v m/s km/h; 1 km/h = 0.278 m/s Acceleration a m/s2 Force F N (newton) 1 kgf (kilogram-force) = 9.8 N Pressure p, P Pa (pascal) mmHg (millimetre of mercury) 1 mmHg = 133.3 Pa atm (atmosphere); 1 atm = 101 325 Pa mbar (millibar); 1 mbar = 100 Pa Energy E J (joule) kWh (kilowatt hour); 1 kWh = 3.6 · 106 J The number and its unit a re sepa rated by a space. The pref i x sy mbol is w r it ten before the un it , w ith no space bet ween them. 3 μm The sy mbol of the unit is in lower case, except i f it refers to the name of a person: m (metre), J ( jou le). A f ter the sy mbol of a un it , there is no f u l l stop or "s" to ind icate a plu ra l . 18 Which of these properties of matter are quantities? a) Colour b) Temperature c) Attractiveness d) Speed e) Price f ) Volume 19 Which of these terms are quantities and which are units? litre – newton – metre – acceleration – ampere – kelvin – candela – second – mole 20 Complete the tables in your notebook. Name Symbol … ns exagram … gigajoule … … dA … cL femtometre … Name Symbol milligram … … hL terametre … … pJ kilolitre … … Mg A C T I V I T I E S Many un its belong to the decima l metr ic system. Thei r mu lt iples and submu lt iples a re related to each other by powers of 10. 1 21
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