i nternational system of units 3.2. i nternational system of units abbreviated si (systeme...
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INTERNATIONAL SYSTEM OF UNITS
Abbreviated SI (Systeme International d’Unites)
A revised version of the metric system.
Adopted by international agreement in 1960.
7 SI base units, all other units are derived from these.
SI BASE UNITS
Quantity SI Base Unit Symbol
Length Meter M
Mass Kilogram kg
Temperature Kelvin K
Time Second s
Amount of Substance Mole mol
Luminous intensity Candela cd
Electric Current Ampere A
COMMONLY USED METRIC PREFIXES Mega (M) 1 million times larger than the unit it
precedes (106 ) Kilo (k) 1000 times larger than the unit it precedes (103 ) Deci (d) 10 times smaller than the unit it precedes (10-1 ) Centi (c) 100 times smaller than the unit it precedes (10-
2 ) Milli (m) 1 million times smaller than the unit it precedes
(10-3) Micro (µ) 1 million times smaller than the unit it
precedes (10-6 ) Nano (n) 1000 million times smaller than the unit it
precedes (10-9 ) Pico (p) 1 trillion times smaller than the unit it precedes
(10-12 )
MASS VS. WEIGHT
Mass is the amount of matter in an object and is not dependent on gravity.
Weight is the measure of the gravitational pull on an object.
UNITS OF TEMPERATURE
Temperature is a measure of how hot or cold an object is.
Scientists often use the celsius scale when doing experiments.
The kelvin scale is also used. K = ºC + 273 ºC = K – 273 Example: Convert 100 ºC to kelvin. 100 ºC + 273 = 373 K Example: Convert 400 K to ºC . 400- 273= 127 ºC
UNITS OF ENERGY
Energy is the capacity to do work or to produce heat.
The joule (J) and the calorie (cal) are common units of energy.
1 J = 0.2390 cal 1 cal = 4.184 J Convert 4 J to cal. 4 J x 0.2390 cal 1 J=0.956 cal
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