Megaton
Encyclopedia : M : ME : MEG : Megaton
A megaton or megatonne is a unit of mass equal to 1,000,000 metric tons, i.e. 109 kg or 1 teragram (Tg). The official SI symbol for the megaton is Mt, but MT is also being used; beware that the latter is the SI symbol for megatesla and also (unofficially) used for the metric ton in some contexts. See 1 E9 kg for a comparison with similar masses.
The kiloton or megaton of TNT is used as a unit of energy, approximately equivalent to the energy released in the detonation of this amount of TNT. The megaton of TNT has traditionally been used to rate the energy output, and hence destructive power, of nuclear weapons. This unit is written into various arms control treaties, and gives a sense of destructiveness as compared with ordinary explosives, like TNT. More recently, it has been used to describe the energy released in other highly destructive events, such as asteroid impacts.
- A gram of TNT by definition for arms control purposes is 1000 thermochemical calories, which equals 4.184 kilojoules (kJ).
- A ton of TNT, (a metric ton = 1000 kg) is therefore 4.184 × 109 J = 4.184 gigajoules (GJ).
- A kiloton of TNT is therefore 4.184 × 1012 J = 4.184 terajoules (TJ).
- A megaton of TNT is 4.184 × 1015 joules = 4.184 petajoules (PJ).
- A gigaton of TNT is 4.184 × 1018 joules = 4.184 exajoules (EJ).
- A teraton of TNT is 4.184 × 1021 joules = 4.184 zettajoules (ZJ).
The measured pure heat output of a gram of TNT is only 652 thermochemical calories = 2724 J [link], but this is not the important value for explosive blast effects calculations.
See also
References
- Rhodes, Richard. The Making of the Atomic Bomb, New York: Simon and Schuster, 1986.
- Cooper, Paul. Explosives Engineering, New York: Wiley-VCH, 1996.
From Wikipedia, the Free Encyclopedia. Original article here. Support Wikipedia by contributing or donating.
All text is available under the terms of the GNU Free Documentation License See Wikipedia Copyrights for details.