Page 517 - Canadian BC Science 9

SI Units
In science classes, you will often be instructed to report your measurements and answers in SI units. The term SI is taken from the French name Le Système international d’unités. In SI, the unit of mass is the kilogram, the unit of length is the metre, the unit of time is the second, the unit of temperature is the kelvin, and the unit of electric current is the ampere. Nearly all other units are defined as combinations of these units.
Example 1
Convert 527 cm to SI units.
Solution
The SI unit of length is the metre. 1 m 􏰀 100 cm
527cm× 1m =5.27m 100 cm
Example 2
Convert 3.2 h to SI units.
Solution
The SI unit of time is the second. 1 min 􏰀 60 s; 1 h 􏰀 60 min
3.2h × 60min × 60s = 11520s h 1 min
Frequently Used Scientific Quantities, Units, and Symbols
Quantity
Unit
Symbol
length
nanometre micrometre millimetre centimetre metre kilometre
nm 􏰈m mm cm m km
mass
gram kilogram tonne
g kg t
area
square centimetre square metre hectare
cm2 m2
ha
volume
cubic centimetre cubic metre millilitre
litre
cm3 m3
mL L
time
second
s
temperature
degree Celsius
˚C
force
newton
N
energy
joule kilojoule
J kJ
pressure
pascal kilopascal
Pa kPa
electric current
ampere
A
quantity of electric charge
coulomb
C
electrical resistance
ohm
􏰉
frequency
hertz
Hz
power
watt
W
Instant Practice—Using Metric Measurements
1. A hummingbird has a mass of 3.5 g. Express its mass in mg.
2. For an experiment, you need to measure 350 mL of dilute acetic acid. Express the volume in L.
3. A bald eagle has a wingspan up to 2.3 m. Express the length in cm.
4. The heaviest blue whale ever recorded was a massive 190 tonnes. Express its mass in grams.
5. A student added 0.0025 L of food colouring to water. Express the volume in mL.
Instant Practice—Converting to SI Units
Convert the following quantities to SI units.
1. 52km
2. 43 min
3. 8.63 g
4. 45 973 mm
5. 537891cm
6. 1.75 h
7. 16 Mg (megagrams) 8. 100 km/h
Science Skill 13 • MHR 499