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The '''TNT equivalent''' is a unit of [[Energy (science)|energy]] commonly used to quantify the energy released (or "yielded") in [[Explosives|explosions]]. The ton (or tonne)<ref name=ton group=note/> of TNT equivalent is equal to 4.184 gigajoules (GJ)<ref name=NIST/> which is approximately the amount of energy released in the [[detonation]] of one ton of [[TNT (explosive)|TNT]]<ref name=TNT group=note/> [[explosive]].
The units, kiloton and megaton of TNT, have commonly been used to rate the energy yield, and hence destructive power, of [[nuclear weapon]]s. These units have been used in various nuclear weapon control treaties<ref name=treaty/> as well as in numerous article and books.
==Amounts, symbols and energy yields==
Various tonnages of TNT equivalent energy and their commonly used energy yield expressions are tabulated below:
{| class="wikitable"
! Amount  of<br/> TNT equivalent
! Symbol
! colspan=3|Energy yield<br/>(three equal expressions)
|- align=center
|ton ||t ||4.184 gigajoules||4.184 GJ||4.184×10<sup>9</sup> J
|- align=center
|kiloton||kt||4.184 terajoules||4.184 TJ||4.184×10<sup>12</sup> J
|- align=center
|megaton||Mt||4.184 petajoules||4.184 PJ||4.184×10<sup>15</sup> J
|- align=center
|gigaton||Gt||4.184 exajoules||4.184 EJ||4.184×10<sup>18</sup> J
|}
==Some example usages==
*The [[GBU-43 Massive Ordnance Air Blast|Massive Ordinance Air Blast]] (MOAB) bomb, the largest conventional bomb ever produced in the [[United States]], has a TNT equivalent energy yield of approximately 11 tons (11 t). 
*The [[W54 (nuclear weapon)|W54 nuclear warhead device]], now retired, developed by the United States in the early 1962s, had a TNT equivalent energy yield of 10 to 20 tons (10 to 20 t) and was probably the smallest nuclear device ever produced in the United States.
*The code-named [[LITTLE BOY (nuclear weapon)|Little Boy]] nuclear fission bomb air-dropped by the United States on [[Hiroshima, Japan]] in [[World War II]] had a TNT equivalent energy yield of approximately 15 kilotons (15 kt).
*During the [[Cold War]] that followed World War II, the United States tested a nuclear weapon that had a TNT equivalent energy yield of 15 megatons (Mt) and the [[Soviet Union]] tested a nuclear weapon with a TNT equivalent energy yield of 50 megatons (Mt).
*The magnitude 9.0 [[Tohoku-Oki earthquake]] that occurred off the east coast of [[Japan]] on March 11, 2011 has been estimated to have released 9.1×10<sup>18</sup> joules which amounts to TNT equivalent of 2,175 megatons (Mt) or 2.175 gigatons (Gt).<ref name=ScienceMag/>
==Notes==
{{reflist|group=note|refs=
<ref name=ton group=note>The "ton" usually refers to the "short ton" that is a [[U.S. customary units|U.S. customary unit]] equal to 2,000 [[pound]]s which, in turn, equals 0.907 [[tonne]] (the metric ton which is 1,000 [[kilograms]]). In the context of using TNT equivalents, a ton is taken to be synonymous with a tonne and both are defined as being equal to 1,000 kilograms.</ref>
<ref name=TNT group=note> TNT is [[trinitrotoluene]], an explosive chemical compound with the formula C<sub>6</sub>H<sub>2</sub>(NO<sub>2</sub>)<sub>3</sub>CH<sub>3</sub>. Its [[IUPAC]] name is 2-methyl-1,3,5-trinitrobenzene.</ref>
}}
==References==
{{reflist|refs=
<ref name=NIST>[http://physics.nist.gov/Pubs/SP811/appenB8.html NIST Guide to SI Units, Appendix B.8 Factors for Units Listed Alphabetically] NIST defines the ton of TNT equivalent as being exactly 4.184 GJ.</ref>
<ref name=treaty>{{cite journal|author=F.A. Long|title=Peaceful Nuclear Explosions|journal=The Bulletin of the Atomic Scientists|volume=32|issue=8|pages=pp. 18-28|date=October 1976|url=http://books.google.com/books?id=4QsAAAAAMBAJ&pg=PA18&lpg=PA18&dq=%22treaty%22+megaton+OR+kiloton&source=bl&ots=K1-xfSn4Fc&sig=hZMq4epC0Z30wI_8-MRpPXjGAyE&hl=en&ei=mS_xTenQDuqq0AGm6IDjDw&sa=X&oi=book_result&ct=result&resnum=5&ved=0CCgQ6AEwBA#v=onepage&q=PNE%20treaty&f=false}}</ref>
<ref name=ScienceMag>{{cite journal|author=Satoshi Ide, Annemarie Baltay and Gregory C. Beroza|title=Shallow Dynamic Overshoot and Energetic Deep Rupture in the 2011 Mw 9.0 Tohoku-Oki Earthquake|journal=Science|American Association for the Advancement of Science (AAAS)|date=May 19, 2011 online|url=http://www.sciencemag.org/content/early/2011/05/18/science.1207020.full.pdf}}</ref>
}}

Revision as of 20:32, 16 June 2011