[Home][General][Business][Engineering][VCE][Learning Units][Tool Box][Glossary]

Measurement
Units & Conversions
Examples
Have a Go
Practice Questions
 


Back to
Measurement Units

These are some of the things that we measure in everyday living.

*  time                                *   distance or length            *  speed
*  temperature                   *   area                                 *   money
*  mass                               *   volume                             * capacity

To measure quantities like this, units of measurement are required. The system of units we use in Australia is called the metric system. Calculations in metric system is easy, because they are based on powers of 10 just like in our decimal system. The following units are most commonly used and it is important to remember their symbols(or shortened form).

Quantity Name of unit Symbol Value
length millimetre
centimetre
metre
kilometre
mm
cm
m
km
10mm   = 1cm
100cm  =  1m
1000m  =  1km
mass milligram
gram
kilogram
tonne
mg
g
kg
t
1000mg = 1g
1000g  = 1kg
1000kg = 1t
time second
minute
hour
day
s
min
h
day
60s = 1min
60min = 1h
24h = 1day
temperature degrees Celcius C
area square millimetre
square centimetre
square  metre
hectare

 




volume cubic millimetres

cubic centimetres

cubic metres

capacity
(volume of fluids)
millilitre
litre
kilolitre
mL
L
kL
1000ml = 1 L
1000L  = 1kL
speed metres per second
kilometres per hour

Units in blue are standard units.

Remember !

To convert small units into large units you divide. ( )

To convert large units to small units you multiply. ( )

 

In Engineering and in Sciences, we use very larger units as well as very smaller units. Here are the some of the prefixes and the symbols and their values.

 

 

 

 

Examples

(1) Let's convert 250cm to metres.
     100cm  =  1m
     250cm  =  250 100
                 =   2.5m
centimetre(cm) is the smaller unit than the metre, so to convert smaller unit to a larger unit we divide. 100cm = 1m , we divide by 100.
(2) Let's convert 2.8kg to grams.
      1kg    =   1000g
      2.8kg =   2.8 1000
                =   2800g
kilogram is the larger unit than the gram, so to convert larger unit to a smaller unit, we multiply by the factor.
1kg = 1000g, we multiply by 1000.
(3) Let's convert 100milliamperes(mA) to              amperes(A)
     1000mA = 1A
      100mA  = 100 1000
                    = 0.1A

      
                         

milliampere(mA) is the smaller unit than the ampere(A), so to convert smaller unit to a larger unit we divide by the factor.1000mA = 1A, we divide by1000.

In Engineering and in Sciences we use scientific notation for cacculations. Instead of the term "milli" we can put 10-3

 

 

 

 

Return to Top of Page

 

 

 

 

 

 

Have a Go

Problem 1 
Convert:
(a) 180 cm to metres (m)

(b) 1.5 minutes to seconds(sec)

(c) 250 milligrams(mg) to grams

 

See Solution

 

 

Problem 2
Convert:
(a) 300 millivolts (mV) to volts

(b) 2800 megavolts to volts

(c) 0.002amperes(A) to
     microamperes(A) 

 

See Solution

 

Return to Top of Page

 

 

 

 

 

 

Practice Questions

Question 1
Convert 1500ml to litres.

 

 

Question 2
Convert 90sec to minutes.

 

 

 

Question 3
Convert 2.25km to centimetres.

 

 

Question 4
Convert 1750g to kilograms.

 

 

Question 5
The current of a circuit is 5 10-5 A. Convert this current to microamperes.

 

 

Question 6
Convert 1000 000 Watts to megawatts.

 

 

 

Return to Top of Page

 

 

 

 

 

 

Solution 1

(a) 180cm to metres
     100cm = 1m
     180cm = 180 100
                = 1.8m
Remember:
smaller units to larger units you divide()
(b) 1.5 minutes to seconds(sec)
      1min  =  60 sec
      1.5min = 1.5 60
                 = 90 sec
larger units to smaller units you multiply()
(c) 250mg to grams
     1000mg = 1g
       250mg = 250 1000
                  = 0.250g
smaller units to larger units you  divide ()
when dividing by 1000 you move the decimal point in 250.0, three places to the left.

 

 

back to Have a Go

 

Solution 2

(a) 300mV to V
     method 1
     300mV = 300 10-3
                 = 3102 10-3
                      = 3 10-1
                      = 0.3 V


    method 2
    300mV = 300 1000
                 = 0.3 V
method 1
Remember:
Instead of "milli" we can put " 10-3 "



method 2
1000mV = 1 V
smaller units to larger units you  ,
when dividing by 1000 you move the decimal point in 300.0, three places to the left.
(b) 2800MV to V
           1MV = 106 V
     2800MV = 2800 106 V
                    = 2.8 103 106 V
                    = 2.8 109 V
Remember:
Instead of "mega" we can put " 106 "
(c) 0.002A to microamperes(A)
           1 A = 106 A
     0.002A = 0.002 106 A
                  = 2 10-3 106 A
                  = 2 103 A
                  = 2000 A
microampere the smaller unit, ampere the larger unit,
A to A that is larger to smaller units you muutiply ()

 

back to Have a Go

Return to Top of Page

 

 

[Home][General][Business][Engineering][VCE][Learning Units][Tool Box][Glossary]