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I thought that ltr referred to liquid weight and Kgs was dry weight. I'm now totally confused one seller is selling in a plastic tub weight 5ltrs the other seller is selling in a plastic sack/bag weight 5Kg. Are the same amount/volume or whatever or is 5ltrs more than 5Kg or are they the same weight.
I'd prefer pounds and ounces but I'm old school making me old😁. Any help would be much appreciated and educational. Many thanks
A litre is a measure of volume, whereas kilogramme is a measure of mass (weight).
Where a material has unity density, a 1 litre volume will have a mass of 1kg.
I’m a bit surprised that the bird seed is sold by the litre because if you were to take a vessel that holds a litre and poured in the bird seed, because of the gaps (between the seeds) the total volume of bird seed would be less than a litre. In fact if the bird seed had unity density, 1 litre of bird seed would weigh less than 1kg for this reason.
In defence of the bird seed manufacturer, there may be a potential issue with the seeds drying out over time, reducing their weight, whereas the change in volume would not be as pronounced.
You will normally see such a disclaimer on bags of compost (that are sold by volume), that may be subject to a slight reduction in volume due to drying.
"In fact if the bird seed had unity density, 1 litre of bird seed would weigh less than 1kg for this reason."
As indeed it does. The density of bird seed obviously varies, but the average densiy is about 0.6kg per litre. So a five litre sack would weigh about 3kg.
"You will normally see such a disclaimer on bags of compost (that are sold by volume), that may be subject to a slight reduction in volume due to drying."
Eiher that or they may say (for example) "25 litres when packed".
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