Density table.

[Ben from Vic.]

Here's a very interesting link I came across while looking for the density of the American Hornbeam tree.

They also call it Ironwood. It's not even as heavy as TO.


Density table.



Ben.

[Soren]

"Back in the old days" I was taught that 1 litre of water would weigh in at 1 kg, and would fill a volume of 1000 cubic cm, ie 10 * 10 * 10.
Following that reasoning, I would expect that 1 cubic metre of water, would weigh 1000kg.
I was surprised to see from the table that fresh water is quoted at 993.1kg / M3 and salt water at 1025.2kg /m3
I know that the weight is relative to the height above sea level, where the measurements are taken, but I would have thought that fresh water might have been quoted at 1000, or do we need to add a factor to every other figure given ? :confused:

[simon c]

Soren, just a few things to clarify.

A litre is not an SI unit and it is equal to the volume occupied by 1 kg of water at 4 deg C and 1 atm pressure. The reason for choosing 4 deg C is that water is at it's most dense at that temperature. If the temperature gets lower or higher, it will start to expand.

SI units, (the kg and the meter) are not defined using water but on a lump of metal in Paris and the wavelength of some radiative substance. When refering to density to that degree of accuracy, you should always quote the temperature and pressure that the measurement is for. The density of water in SI terms is normally quoted at 25 deg C, when it expands to occupy a higher volume and is therefor lighter (approx 998 kg/m3).

Mass (as opposed to weight) does not vary with height above sea level, but density will due to expansion. The reason that salt water is more dense than fresh water is that it includes the weight of the salt in the water (ie there is approx 25g of salt and other things for each "litre" of sea water). When salt dissolves in water the mass goes up but there is no equivalent change in volume as the water takes the salt ions into the existing water molecule structure.

Where they get the 993 from for fresh water I'm not sure and it appears to be a bit suss so I would only use this website as guide for wood and not for accuracy of other values as they don't quote temp and pressure.

Simon

[Soren]

Soren, just a few things to clarify.


..... I would only use this website as guide for wood and not for accuracy of other values as they don't quote temp and pressure.

Simon

exactly the point I was trying to make