Well there you go they are all related.... the aforementioned metre when arranged in three dimensions (a cube) and filled with water at its triple point will weigh exactly 1000 kilograms! That is the beauty of the SI system. There are a minimum number of easily defined basic units, length temperature, time and I think energy. and every other unit is drived from those basic units. Unlike the mile which I think was defined by the length of a roman soldiers stride. and the horse power which was defined by the obvious. Bloody lucky I was not a roman soldier because the mile would be somewhat shorter than it is.
