Mass
Mass
The basic unit for the measurement of length is the metre. When mass (the weight of something) is being measured, the basic unit of measurement is the kilogram. A kilogram (kg) is 1 000 grams (g).
The gram is used to measure small weights, and the tonne (t) is used for larger weights: 1 000 g = 1 kg and 1 000 kg = 1 tonne.
Grams
A gram is one thousandth of a kilogram (0.001 kg). Things which might have a mass of a single gram include items such as a paperclip or a marble. One millilitre of water (a cubic centimetre of it) also has a mass of 1 gram.
Some comparative gram amounts
Mass |
Object |
1 g |
a marble |
50 g |
a small box of powdered soup |
375 g |
a small tub of margarine |
850 g | a tin of canned fruit |
950 g | a large box of breakfast cereal |
1 000 g | half a dozen large apples |
5 000 g | a large bag of potatoes |
See animation
The relationship of the millilitre to the cubic centimetre
One litre (1 000 mL) is the amount of water that would have a mass of exactly 1 kilogram (1 000 g). A single millilitre has a mass of 1 gram and occupies the space of 1 cm^{3}.
Converting grams to kilograms (g kg)
As there are 1 000 grams in a kilogram, to convert g to kg is simply a matter of dividing by 1 000. This means moving the decimal point 3 places to the left.
Example:
8 000 g 8 000 1 000 8 kg
6500 g 6 500 1 000 6.5 kg
454 g 454 1 000 0.454 kg
Converting kilograms to grams to (kg g)
As a kilogram equals 1 000 grams, to convert kg to g is simply a matter of multiplying by 1000. This means moving the decimal point 3 places to the right.
Example:
6 kg 6 x 1 000 6 000 g
8.7 kg 8.7 x 1 000 8 700 g
0.049 kg 0.049 x 1 000 49 g
Several different notations for expressing mass
Masses involving grams and kilograms can be written in a number of different notations. They may be written as quantities:
i) in grams
ii) in both grams and kilograms, or
iii) in kilograms, using decimal notation.
Gram |
2 365 g |
1 800 g |
450 g |
84 g |
kilogram and gram |
2 kg 365 g |
1 kg 800 g |
450 g |
84 g |
Decimal notation (kg) |
2.365 kg |
1.800 kg |
0.450 kg |
0.084 kg |