I have a question about metric system. The following story comes from RD. "Adventures of a Chinese Carpet."
"It (rug) was a beauty, 9-by-12 feet of wool, so finely woven that it seemed to have no pile."
(9 means width? length?)
ANSWER: When you speak of width (breadth), you are speaking of the distance from side to side. It is the horizontal measurement taken at right angles to the length. When you speak of length, you are speaking of the distance from end to end. It is the longer vertical measurement. Thus, the rug has a width of 9 feet and a length of 12 feet.
(What if something, usually it could be a cube, is described 4-6-7 inches of wood, what does three number mean? 4 means width, 6 means length, 7 means height?)
ANSWER: A cube by definition is a regular solid of six equal square sides, such as dice. Thus, for discussion, its width, length, and height (depth) dimensions would be the same, either 4-4-4 or 6-6-6 or 7-7-7 inches.
Now, by definition the greatest of the two or three dimensions of anything is length. However, if you have a solid block of wood or plastic or brick having all flat surfaces that is 4-by-6-by-7 inches (a cuboidal rectangular box), then, the height by definition must be vertical from the bottom to the top of it as viewed and measured from its sitting position on a surface. Thus, the height depends on which side or face the block is turned and sitting on. The other two remaining dimensions will then follow in order and obey the rule that the longest dimension is the length and the shortest dimension is the width.
In general, 4x6x7 means WxLxH and usually you find it so written in most math and physics texts, nevertheless, you will at times see it written as LxWxH. Often, an accompanying diagram aids in visualizing and analyzing the physical situation. Numbers in and of themselves, as 4-6-7 inches of wood, leaves you with a lot of guesswork.
In the building trades, you often see lumber 2"x 4" (2 inches-by-4 inches), also written two-by-four. Here, it is speaking of thickness (depth or height)) x width, and having any desired length of cut.
I hope this is not confusing. If you need a little more clarity on any particular point of it, let me know. "Ambiguous Bill"
