Talk:TNT equivalent

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See also Talk:Tonne of TNT for old discussions.

Contents

[edit] Why TNT?

Can someone add a history section how TNT come to be used as the standard. —Preceding unsigned comment added by SweBrainz (talk • contribs) 5 Nov 2006

[edit] Consolidation

Last night I merged Tonne of TNT and material from Ton here, since there was a lot of redundant content. I also re-redirected kiloton and a number of similar redirects to point at ton and not here, since they are often used to speak of mass rather than explosions. I don't claim to have done this perfectly, so please be bold in following up on it. I didn't see any existing controversy over this terms, but if I have created one, I'm willing to discuss. --Strait 17:17, 7 February 2007 (UTC)

Part of what I'd put in section below moved up here Gene Nygaard 03:50, 8 February 2007 (UTC)
I'd also like to discuss your related moves, such as changing megaton to a redirect to ton after that was expanded and also linked to this newly expanded article as a "Main article". While I think that has some good points, there are factors that need to be discussed.
For one thing, the various moves have left an orphaned talk page without an associated article, which I linked to at the top of this page.
For another thing, right or wrong, the "megaton" article dealt primarily with energy equivalent of TNT. (Note that after your moves, we need to go to the history of the redirect at "Tonne of TNT" here to see what it said.) The "ton" article deals primarily with mass, but also many other meanings of the highly ambiguous word. But most of the links to "megaton" were to the TNT equivalent meaning.
Those links should all be cleaned up. Not only to link to a more specific article, but also to specify the units, in the visible text in the articles containing those links, as "tons of TNT" or something of the sort, not just "tons" and "kilotons" and "megatons" as if they were units of mass rather than energy.
One of the problems is that if people are talking about wheat production, for example, they rarely use "megatons". Those mass units usually "million tons" or "million metric tons" or "million tonnes" or "million metric tons" in that context. And even if the tons are not identified as metric tons in that context, they almost always are—because even in the U.S. metric tons are the only tons in general use for that purpose. When these numbers are not expressed in metric tons in the United States, they are not expressed in short tons either, but rather in bushels as units of mass, with 1 bushel of wheat or soybeans ≡ 0.0272155422 (metric) ton, 1 bu of corn or rye ≡ 0.02540117272 metric ton, 1 bu of barley ≡ 0.02177243376 metric ton, etc.
Another is that nobody talks about "short megatons" or "long megatons"; megatons (even if not dealing with energy) are almost always metric tons. But a large part of the "ton" article deals with all the various distinctions between long, short, and metric tons not only in the mass units and the force units, but sometimes in energy or power units or whatever. Gene Nygaard 19:39, 7 February 2007 (UTC)


[edit] contradiction

Gene Nygaard: You removed the contradiction tag from the "values" section. I was not confused about the meaning of "convention". Here I have highlighted the problem:

A gram of TNT releases 980–1100 calories upon explosion. To define the tonne of TNT, this was arbitrarily standardized to 1000 calories = 1 gram TNT.
This definition is a conventional one. Explosives energy is normally calculated using the thermodynamic work energy of detonation, which for TNT has been accurately measured at 1120 cal/g from large numbers of air blast experiments and theoretically calculated to be 1160 cal/g.

Not only does the second figure fall outside of the range of the first, but the first figure implies that the value is either inconsistent or poorly measured, whereas the second does not. --Strait 17:24, 7 February 2007 (UTC)

That says, to me at least (but maybe just because I know that, and the wording may need to be tweaked), that the term "ton of TNT equivalent" always means a gigacalorie, derived from a conventional value of 1000 cal/g times a million grams. It doesn't matter what the actual energy TNT produces. But the article tries to explain that in one way of measuring that, it is higher than the conventional value, and that in another way of measuring it, it is lower than the conventional value used to define a "ton of TNT equivalent". The problem may be that not everyone will understand what the word "conventional" means in this context, so the transition to measurements made in different ways needs to be made more clear. [part moved up, re-signed here Gene Nygaard 03:50, 8 February 2007 (UTC)]

It appears that there is an error in the section about Blast Radii and the R = \left( \frac{E t^2}{\rho} \right)^{\begin{matrix}\frac{1}{5}\end{matrix} } equation. It's stated that G.I. Taylor arrived at a figure of 22 kilotons for the yield of the Trinity device based on a 140m fireball radius at 0.025 seconds into the explosion. However, when I ran the equation myself today (just an exercise in keeping the mind healthy) my result was closer to the officially stated yield of 20 kilotons than the 22 kiloton figure.

The equation I used was a transformation of the above equation to solve for E - E = \frac{R^5 \rho}{t^2} - which, unless every math teacher I had in school a decade ago are wrong - is correct. I came up with a figure of approximately 8.6 \times 10^{13} Joules, or about 20.6 kilotons. The difference could very likely be that the article speaks in terms of "approximately 9 \times 10^{13} Joules, which is about 22 kilotons when rounded to the nearest integer.

I wouldn't be complaining about it, but the way the article is written makes it sound like either:

  1. The officially stated yield of the Trinity test device is incorrect …or…
  2. The equation is not actually accurate.

Since I solved the equation myself and have seen that the result matches the official number to within 3% I'm certain that both of the above are false. The official number is likely a truncation of the known yield for ease of public consumption and the approximate 20.6 kiloton figure returned by solving the equation is probably the real yield figure.

As this is an article about a subject I have only a passing familiarity with I do not feel qualified to make an edit to the page, nor I am sure how to note that the stated 22kiloton result (and hence the approximately 10% level of error in the figure) is a result of the rounding done and not a result of the equation being inaccurate. And I'm also not sure if such should be done. - An anonymous Wikipedia user

[edit] Chixculub

The one that killed off (most) dinos might be added to the list. Values should be around. Dysmorodrepanis (talk) 03:54, 26 March 2008 (UTC)