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Which one is better: two pipes of different radii or two pipes of different radius?

In Futurama, let me show you some of the different lengths of wire I use is a plural argument, but is it only because it's more than two?

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up vote 3 down vote accepted

I think it depends on how many of the property are associated with the object. Whether you use plural form for the property can also depend on whether you use "of" or "with"

  • two pipes of different weight.
  • two pipes with different weights.
  • three containers of different volume.

A pipe has many dimensions, for example: length, diameter and wall-thickness. So if you use a more general term like size, you may be saying that a plurality of dimensions may differ.

  • Two pipes of different size.
  • Two pipes with different sizes.
  • Two pipes of different diameter.

The Futurama example is a bit different because the phrase "a length of wire" can be used as a noun. For example one can say "let me show you some of the different heaps of sand I use". So "different lengths of wire" could have the same meaning as "different pieces of wire" - they might differ more in diameter or hue rather than in length.

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Two pipes with different diameters.

Clearly, there are two diameters because the diameters are different.

The same applies to the radii, but you more normally talk in terms of diameters of pipes than radii. (On those occasions when you do use radius in connection with a pipe, it tends to be the radius of the bend in the pipe rather than half the diameter of the pipe.)

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The fact some people prefer talking about diameters of round objects, is an unrelated sickness (see tauday.com) – Pavel Radzivilovsky Jan 3 '11 at 11:33

I don't have an authority to cite, but altering the construction slightly makes it clear to me at least that the plural is called for:

I have two pipes. They have different radii.

You would not say "they have a different radius" unless you were comparing both of your two (same-radius) pipes to a third.

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I believe both work. In the second, the word "each" is implied. So, while there is more than one radius, and you can say that there are pipes of different radii, each pipe only has one radius, and in reference to the radii of the particular pipes themselves (as opposed to the radii of the set of pipes you have available), you may say "two pipes of different radius."

You can have a bunch of people of different height. You can also have a bunch of people with different heights. Ehhh... The word "with" sounds nicer when I used the plural adjective. But yea, I'm pretty sure both are acceptable.

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In the world of many factors and continuities, one necessarily has to be better than the other :) – Pavel Radzivilovsky Jan 3 '11 at 11:37
Also, 'with' sounds rather bad to me - 'with' just sounds like a symmetric relation (unlike of). Consider, for instance "three heights with different people" – Pavel Radzivilovsky Jan 3 '11 at 11:38
It's "people with different heights". – Daniel Jan 3 '11 at 18:49
Also, you might say, "three pipes with different levels of iron." Level of iron is a quality, like radius. So it works. They both work. – Daniel Jan 3 '11 at 18:58

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