I am glad you pointed out the 80g/m^2 = 5g rule of thumb, as I had neglected to mention it in my post. It is easy to calculate, as A4 is 1/16 of 1m^2 , and if the paper weighs 80 grams per square metre, it means 80grams is the weight (mass) of 1 sheet of A0.
Of course, technically, as you alluded to, grams is a unit of mass not weight. The proper SI unit of weight is the Newton (named after British scientist Sir Isaac Newton), but you can also use grams-force, which can be shortened to grams. To those who don't understand the difference between mass and weight remember that your mass is the same wherever you are, on Earth, the Moon, or in space, but weight is a factor determined by gravity, so that your weight on Earth might be 60kgf (kilograms-force) but only 10kgf on the Moon, and 0kgf in space, but your mass will be 60kg in all 3 places.
David
Pat Naughtin wrote:
Dear David,
What you say here is relevant and useful, but have you considered the mass of the paper?
For example, in the example you use of an A4 piece of paper, with an area of 1/16 square metre, this has a mass of 5 grams if the paper is the most common used 80 grams per square metre. I have used this concept for determining the mass of herbs in a recipe when I had no standard masses available.
I know that there is an issue of hygroscopicity that has to do with the current temperature and humidity, but for many practical applications the idea that a piece of A4 paper has a mass of 5 grams is a useful approximation.
Cheers,
Pat Naughtin LCAMS Geelong, Australia
Pat Naughtin is the editor of the free online newsletter, 'Metrication matters'. You can subscribe by sending an email containing the words subscribe Metrication matters to [EMAIL PROTECTED] --
on 2004-06-26 08.00, David King at [EMAIL PROTECTED] wrote:
While most of the world uses the A series of paper, the USA continues on with its own sizes (e.g. Letter). Canada also has its own proprietory paper sizes.
The international A series is very easy to use. The ratio of the sides is always the square root of 2, i.e. divide the length by width and it will ALWAYS equal 1.414. This also means that when a piece of A-sized paper is cut in half along the longest side, the new smaller sheet will have an area that is half the original, and with the ratio of the sides being still the same. This means that, for example, you can stick two pieces of A4 paper together along the longest side and it becomes one sheet of A3, or vice versa, cut an A3 sheet into two A4 sheets.
To calculate the area of any A-series sheet, use this simple formula:
area (in square metres) = 1 / (2^n)
where n = value of paper size, e.g. for A4 paper, n = 4
thus area = 1 divided by ( 2 raised to the power 4 ) = 1 / (2 × 2 × 2 × 2) = 1/16 so an A4 sheet has an area of one sixteenth of one square metre.
Look at A0, put in the 0 and the formula is: area = 1 / (2^0) = 1/1 = 1
A0 has an area of one square metre.
The sizes increase in number by 1 as they halve in area, thus the series goes A0, A1, A2, A3, A4, A5, A6, etc.
The A series of paper is mathematically perfect as well as being very useful in offices around the world where it is used, because of its ability to retain its shape when halved or doubled in area. US paper sizes cannot do this, as the ratio of sides is not 1.414.
--
/*David King*/
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