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Bombing

Bombing

:This article is about explosive devices. This can also refer to water bombs or volcanic bombs. Bomb is also a slang term. Bomb] A bomb is an explosive device which, although not containing more energy than ordinary fuel (except in the case of a nuclear weapon), generates and releases its energy very rapidly, as a violent, destructive shock wave. It is usually some kind of container filled with explosive material, designed to cause random destruction when set off. The word comes from the Greek βόμβος (bombos), an onomatopoetic term with approximately the same meaning as "boom" in English. These are first and foremost weapons; the term "bomb" is not usually applied to explosive devices used for civilian purposes (such as construction or mining). Note that many military explosive devices are not called "bombs". The military mostly calls airdropped, unpowered explosive weapons "bombs," and such bombs are normally used by air forces and naval aviation. Other military explosive devices are called grenades (such as hand grenades), shells, depth charges, warheads (in missiles), or land mines. They have been used for centuries in warfare and are a central part of the terrorist's arsenal. They fall into three distinct categories: conventional (filled with chemical explosives), dispersive (filled with submunitions, chemicals or other disruptive agents which are spread on or shortly before impact) or nuclear (relying on nuclear fission or nuclear fusion for their effect). nuclear fusion A distinction is commonly drawn between terrorist and military bombs. The latter are almost always mass-produced weapons, developed and constructed to a standard design out of standard components and intended to be deployed in a standard way each time. By contrast, terrorist bombs are usually custom-made, developed to any number of designs, use a wide range of explosives of varying levels of power and chemical stability, and are used in many different ways. For this reason, they are generally referred to as improvised explosive devices or IEDs. The most powerful bomb in existence is the hydrogen bomb, a nuclear weapon. The first nuclear bomb ever to be used in combat was dropped by the United States to attack Hiroshima and Nagasaki. The most powerful non-nuclear bomb is the United States Air Force's MOAB (Massive Ordnance Air Burst). The most powerful bomb ever was Tsar Bomba: ca. 50 Mt; it had a mass of 27 tons; it was dropped from a bomber for a test, but was for various reasons not very suitable for combat. The first hydrogen bomb Ivy Mike (10.4 Mt) was even heavier in mass, 82 tons. It was too heavy to be deliverable by a plane or rocket, and therefore not very suitable for an attack. [http://www.makeitlouder.com/Decibel%20Level%20Chart.txt Various bomb explosion power levels]

Delivery

The usual method of delivering bombs to their target is by bombing, i.e. dropping them from a bomber airplane. Modern bombs, precision-guided munition, may be guided after they leave an airplane by remote control or (in the case of nuclear weapons) mounted on a guided missile. Some bombs are equipped with a parachute, such as the World War Two "parafrag" (an 11kg fragmentation bomb), the Vietnam-era daisy cutters, and the bomblets of some modern cluster bombs. Parachutes slow the bomb's descent, thus giving the dropping aircraft time to get to a safe distance from the explosion. This is especially important with airburst nuclear weapons. A hand grenade is usually delivered by being thrown. A bomb may also be positioned in advance and concealed, e.g. in a car or truck or by the roadside, in a building (booby trap), in lugguage in a plane, etc. The Blue Peacock nuclear mines (also called nuclear bombs) were planned to be positioned during wartime, and be constructed such that if they were disturbed they would explode within ten seconds. In the case of suicide bombing the bomb is often carried by the attacker on his or her body.

Detonation

The explosion of the bomb has to be triggered by a detonator (fuse/fuze), usually by a clock, a remote control, or some kind of sensor, usually pressure (altitude), radar, or contact.

Bombing

Bombing may be directed at military targets such as ships or armament factories or at civilian targets such as office buildings or cities. Bombing of particular targets such as ships or tanks is called tactical bombing; bombing of areas such as military bases or cities is called strategic bombing. Strategic bombing of civilian targets is controversial and considered a war crime by some and a defining characteristic of terrorism by others, see terror bombing. Area or carpet bombing of cities using Incendiary bombs may result in a firestorm and extensive casualties especially when it is windy.

Bombing of civilian targets

During World War II there were instances where civilian targets had been bombed—first, during the German invasion of Poland in 1939 and the Netherlands (Rotterdam), then following The Blitz directed at London and other British cities and the British bombing of German cities such as Dresden. Towards the end of the Pacific War, when air defense over Japanese cities had become weak, U.S. Strategic Air Forces in the Pacific engaged in extensive bombing of Japanese cities such as Tokyo. This campaign culminated in the bombing of Hiroshima and Nagasaki with atomic weapons, which would play a major part in ending the war. Due to the huge size of a nuclear blast, such weapons can either intentionally or unintentionally cause massive civilian casualties both from the initial blast and subsequent nuclear fallout.
- BLU = Bomb/mine Live Unit
- GBU = Guided Bomb Unit
- LGB = Laser Guided Bomb
- C4 = a type of plastic explosive

Bombing in peacetime

One use for bombing by aircraft in peacetime is to break ice dams that form on some rivers.

External links

- [http://www.fas.org/man/dod-101/sys/dumb/bombs.htm Bombs for Beginners]
- [http://www.makeitlouder.com/document_bombshockwaveestimation.html How a bomb functions and rating their power] Category:Explosive weapons Category:Technology ja:爆弾 simple:Bomb th:ระเบิด

Water bomb

A water bomb, or water balloon, is a simple small latex rubber balloon filled with tap water. The user then throws the water filled balloon at a desired target and the balloon pops leaving the target soaked with water. They are commonly used by children in outdoor play-fights, and by others in carrying out practical jokes, see also balloon. There is also a way of folding a sheet of paper to form a roughly spherical container (see Origami) capable of holding water for some time. These are then filled and thrown in a similar way to the latex version. Water bombs have one main accessory known as the "water balloon launcher". This can be bought at a toy store or homemade with surgical tubing and a piece of soft leather. The launcher can be used to project the water ballon several hundred feet onto an unsuspecting target. Category:Balloons

Volcanic bomb

A lava bomb is a globule of molten rock (tephra) larger than 2.5 inches (64 mm) in diameter, formed when a volcano ejects viscous fragments of lava during an eruption. They cool into solid fragments before they reach the ground. Lava bombs can be thrown many kilometres from an erupting vent, and often acquire aerodynamic shapes during their flight. If the outside of a lava bomb solidifies during its flight, it may develop a cracked outer surface as the interior continues to expand. This type of lava bomb is known as a breadcrust bomb. If the bomb remains molten when it strikes the ground, it may form a distinctively-shaped cow-dung bomb. Volcanic bombs are a significant volcanic hazard, and can cause severe injuries and death to people in an eruption zone. One such incident occurred at Galeras volcano in Colombia in 1993; six people near the summit were killed and several seriously injured by lava bombs when the volcano erupted unexpectedly.

External links

http://www.gc.maricopa.edu/earthsci/imagearchive/bombs.htm
- http://volcanoes.usgs.gov/Products/Pglossary/bomb.html Category:Volcanology

Explosion

drops at an airshow.]] An explosion is a sudden increase in volume and release of energy in a violent manner, usually with the generation of high temperatures and the release of gases. An explosion causes pressure waves in the local medium in which it occurs. Explosions are categorized as deflagrations if these waves are subsonic and detonations if they are supersonic (shock waves). Most common artificial explosives are chemical explosives, usually involving a rapid and violent oxidation reaction that produces large amounts of hot gas. Gunpowder was the first explosive to be discovered and put to use. Other notable early developments in chemical explosive technology were Abel's invention of nitrocellulose (guncotton) in 1865 and Alfred Nobel's invention of dynamite (stabilized nitroglycerin). See the article on explosive material for more detail on chemical explosives. A new order of explosive, the nuclear bomb, was invented in 1945 by the United States military. In 1950, the US military developed the first fusion bomb. Boiling liquid expanding vapour explosions are a type of explosion that can occur when a vessel containing a pressurized liquid is ruptured, causing a rapid increase in volume as the liquid evaporates. Explosions are common in nature. On Earth, most natural explosions arise from volcanic processes of various sorts. Explosive volcanic eruptions occur when magma rising from below has much dissolved gas in it; the reduction of pressure as the magma rises causes the gas to bubble out of solution, resulting in a rapid increase in volume. Explosions also occur as a result of Earth impacts. On other planets, vulcanism and impacts cause explosions with various frequency. Earth impact] Solar flares are an example of explosion common on the Sun, and presumably on most other stars as well. The energy source for solar flare activity comes from the tangling of magnetic field lines resulting from the rotation of the Sun's conductive plasma. Among the largest known explosions in the universe are supernovae, which result from stars exploding, and gamma ray bursts, whose nature is still in some dispute.

Famous explosions

- Chemical explosions
- Halifax Explosion
- Bombay Blasts
- Port Chicago Disaster
- 1887 Nanaimo Mine Explosion
- PEPCON disaster, Henderson, Nevada
- Flixborough disaster
- Hertfordshire Oil Storage Terminal
- Nuclear weapons (nuclear explosions)
- Nuclear testing
- Trinity test
- Castle Bravo
- Tsar Bomba (most powerful nuclear weapon ever created)
- use in war
- Hiroshima
- Nagasaki Nagasaki
- Exploding volcanoes
- Santorini
- Krakatoa
- Mount Tambora
- Mount Pinatubo
- Yellowstone Caldera
- Astronomic-scale events
- The big bang
- Tunguska event
- Comet Shoemaker-Levy 9
- Crab Nebula supernova
- Exploding animals

Nuclear weapon

, 1945, rose some 18 km (11 mi) above the hypocenter.]]
- A nuclear weapon is a weapon which derives its destructive force from the nuclear reactions of nuclear fission and/or fusion. As a result, even a nuclear weapon with a small yield is significantly more powerful than the largest conventional explosives, and a single weapon can be capable of destroying or seriously disabling an entire city. In the history of warfare, nuclear weapons have been used on two occasions, both during the closing days of World War II. The first event occurred on the morning of 6 August 1945, when the United States dropped a uranium gun-type device code-named "Little Boy" on the Japanese city of Hiroshima. The second event occurred three days later when a plutonium implosion-type device code-named "Fat Man" was dropped on the city of Nagasaki. The use of the weapons, which resulted in the immediate deaths of at least 120,000 individuals (mostly civilians) and about twice that number over time, was and remains controversial — critics charged that they were unnecessary acts of mass killing, while others claimed that they ultimately reduced casualties on both sides by hastening the end of the war. (See Atomic bombings of Hiroshima and Nagasaki for a full discussion.) Since that time, nuclear weapons have been detonated on over two thousand occasions, mostly for testing purposes, chiefly by the following seven countries: the United States, Soviet Union, France, United Kingdom, People's Republic of China, India and Pakistan. These countries are the declared nuclear powers (with Russia inheriting the weapons of the Soviet Union after its collapse). Various other countries may hold nuclear weapons, but they have never publicly admitted possession, or their claims to possession have not been verified. For example, Israel has modern airbourne delivery systems and appears to have an extensive nuclear program (see Israel and weapons of mass destruction); North Korea has recently stated that it has nuclear capabilities (although it has now stated that it will abandon all of its nuclear weapons programs); Ukraine may possess an obsolete Soviet-era nuclear stockpile due to a post-Soviet administrative error; and Iran is believed to be attempting to develop nuclear capabilities (for more information see List of countries with nuclear weapons). Nuclear weapons in modern times have been used primarily as a method of creating a strategic threat. For example, the worry that North Korea will use nuclear weapons has dominated the relations between the United States and North Korea. Apart from their use as weapons, nuclear explosives have been proposed for various non-military uses.

Types of nuclear weapons

non-military uses The simplest nuclear weapons derive their energy from nuclear fission. A mass of fissile material is rapidly assembled into a critical mass, in which a chain reaction begins and grows exponentially, releasing tremendous amounts of energy. This is accomplished by rapidly creating supercriticality, either by shooting one piece of subcritical material into another, or compressing a subcritical mass. A major challenge in all nuclear weapon designs is ensuring that a significant fraction of the fuel is consumed before the weapon destroys itself. These are colloquially known as atomic bombs. More advanced nuclear weapons also contain a nuclear fission device, but the energy is used to trigger nuclear fusion, releasing even more energy. In such a weapon, the X-ray thermal radiation from a nuclear fission explosion is used to heat and compress a capsule of tritium, deuterium, or lithium, in which fusion occurs. These weapons, colloquially known as hydrogen bombs, can be many hundreds of times more powerful than fission weapons. The so-called "Teller-Ulam design" is thought to be applied for megaton range thermonuclear weapons. More exotic nuclear weapons also exist, designed for special purposes. The detonation of a nuclear weapon is accompanied by a blast of neutron radiation. Surrounding a nuclear weapon with suitable materials (such as cobalt or gold) creates a weapon known as a salted bomb. This device can produce exceptionally large quantities of radioactive contamination. A nuclear weapon may also be designed to permit as many neutrons as possible to escape; such a weapon is called a neutron bomb.

Effects of a nuclear explosion

neutron bomb The energy released from a nuclear weapon comes in four primary categories:
- Blast – 40-60% of total energy
- Thermal radiation – 30-50% of total energy
- Ionizing radiation – 5% of total energy
- Residual radiation (fallout) – 5-10% of total energy The amount of energy released in each form depends on the design of the weapon, and the environment in which it is detonated. The residual radiation of fallout is a delayed release of energy, while the other three forms of energy release occur immediately. The damage from each of the three initial forms of energy release differs with the size (or "yield", see below) of the weapon. Thermal radiation drops off the slowest with distance, so the larger the weapon the more significant the impact of this effect. Ionizing radiation is strongly absorbed by air, so it is only dangerous by itself for smaller weapons. Blast damage falls off more quickly than thermal radiation but more slowly than ionizing radiation. The energy released by a nuclear weapon is generally measured by the explosive power of an equivalent amount of trinitrotoluene, known as the weapon's yield. The yield of nuclear weapons may be rated as equivalent to several kilotons or megatons of TNT. The first fission weapons had yields measurable in the tens of kilotons, while the largest practical hydrogen bombs have yields around 20 megatons. In practice, nuclear weapon yields will vary significantly, from fractional kiloton weapons designed for tactical use on the battlefield (eg. the man-portable Davy Crockett warheads developed by the United States), to the record Tsar Bomba created by the Soviet Union which had a theoretical maximum design yield of around a hundred megatons. Although a nuclear weapon is capable of causing the same destruction as conventional explosives through the effects of blast and thermal radiation, it does so by releasing much larger amounts of energy in a much shorter period of time. Most of the damage caused by a nuclear weapon is not directly related to the nuclear process of energy release, and would be present for any explosion of the same magnitude. In human terms, nuclear weapons are enormously destructive. A weapon with a ten-megaton yield can destroy most of the buildings of a modern city, while a weapon with a hundred-megaton yield (although the deployment of such a weapon would be considered impractical) would set wooden structures and forests alight up to 60-100 miles (100-160 km) from ground zero. A nuclear weapon detonated in the upper atmosphere will also generate an electromagnetic pulse which can disrupt or disable electronic communications and instruments over a wide area, causing more difficulties for those who survive the effects of a detonation. Concerns over the health and environmental effects of nuclear testing led to the passing of the Partial Test Ban Treaty in 1963 which prohibited atmospheric (above-ground), underwater, or outer space nuclear tests (underground testing continued, however). Since most of the effects of nuclear weapons are blast, thermal, or fallout, well-known civil defense efforts could greatly reduce the total loss of life in a nuclear war.

Nuclear strategy

civil defenseed delivery system. Each missile can contain up to ten nuclear warheads (shown in red), each of which can be aimed at a different target. These were developed to make missile defense very difficult for an enemy country.]] Nuclear warfare strategy are ways for either fighting or avoiding a nuclear war. The policy of trying to ward off a potential attack by a nuclear weapon from another country by threatening nuclear retaliation is known as the strategy of nuclear deterrence. The goal in deterrence is to always maintain a second strike status — the ability to respond to a nuclear attack against your country with a nuclear attack of your own. During the Cold War, theorists used game theory to work out models of what sorts of policies could prevent one from ever being attacked by a nuclear weapon. However, many critics have noted that there could be many exceptions to this in practice, and if an attack ever was truly made then many hundreds of thousands if not millions of people would lose their lives as a result. Additionally, the presence of nuclear weapons by one country can spur nuclear proliferation in countries who feel threatened by them and look to deterrence (which requires a nuclear weapon in the first place) as the only solution. Sometimes this theory has been called Mutual Assured Destruction. Weapons which are designed to threaten large populations or to generally deter attacks are known as "strategic" weapons. Weapons which are designed to actually be used on a battlefield in military situations are known as "tactical" weapons. Different forms of nuclear weapons delivery (see below) allow for different types of nuclear strategy, primarily by making it difficult to defend against them and difficult to launch a pre-emptive strike against them. Sometimes this has meant keeping the weapon locations hidden, such as putting them on submarines or train cars whose locations are very hard for an enemy to track, and other times this means burying them in hardened bunkers. Other responses have included attempts to make it seem likely that the country could survive a nuclear attack, by using missile defense (to destroy the missiles before they land) or by means of civil defense (using early warning systems to evacuate citizens to a safe area before an attack).

Weapons delivery

civil defense" weapon dropped on Nagasaki, Japan. These weapons were very large and could only be delivered by larger bomber aircraft.]] Nuclear weapons delivery— the technology and systems used to bring a nuclear weapon to its target—is an important aspect of nuclear weapons relating both to nuclear weapon design and nuclear strategy. Historically the first method of delivery, and the method used in the two nuclear weapons actually used in warfare, is as a gravity bomb, dropped from bomber aircraft. This method is usually the first developed by countries as it does not place many restrictions on the size of the weapon, and weapon miniaturization is something which requires considerable weapons design knowledge. It does, however, limit the range of attack, response time to an impending attack, and number of weapons which can be fielded at any given time. More preferable from a strategic point of view are nuclear weapons mounted onto a missile, which can use a ballistic trajectory to deliver a warhead over the horizon. While even short range missiles allow for a faster and less vulnerable attack, the development of intercontinental ballistic missiles (ICBMs) and submarine-launched ballistic missiles (SLBMs) has allowed some nations to plausibly deliver missiles anywhere on the globe with a high likelihood of success. More advanced systems, such as multiple independently targetable reentry vehicles (MIRVs) allow multiple warheads to be launched at a number of targets from any one missile, reducing the chance of any successful missile defense. Today missiles are by far the most common among systems designed for delivery of nuclear weapons. To make a warhead small enough to fit onto a missile, though, can be a difficult task. "Tactical" weapons (see above) have involved the most variety of delivery types, including not only gravity bombs and missiles but also artillery shells, land mines, and nuclear depth charges and torpedoes for anti-submarine warfare. An atomic mortar was also tested at one time by the United States. Small, two-man portable tactical weapons (erroneously referred to as suitcase bombs), such as the Special Atomic Demolition Munition, have been developed, although the difficulty to combine sufficient yield with portability limits their military utility.

History

Special Atomic Demolition Munition The first nuclear weapons were created by the United States, with assistance from the United Kingdom and Canada, during World War II as part of the top-secret Manhattan Project. While the first weapons were developed primarily out of fear that Nazi Germany would first develop them, they were eventually used against the Japanese cities of Hiroshima and Nagasaki in August 1945. The Soviet Union developed and tested their first nuclear weapon in 1949, based partially on information obtained from Soviet espionage in the United States. Both the USA and USSR would go on to develop weapons powered by nuclear fusion (hydrogen bombs) by the mid-1950s. With the invention of reliable rocketry during the 1960s, it became possible for nuclear weapons to be delivered anywhere in the world on a very short notice, and the two Cold War superpowers adopted a strategy of deterrence to maintain a shaky peace. Nuclear weapons were symbols of military and national power, and nuclear testing was often used both to test new designs as well as to send political messages. Other nations also developed nuclear weapons during this time, including the United Kingdom, France, and China. These five members of the "nuclear club" agreed to attempt to limit the spread of nuclear proliferation to other nations, though at least three other countries (India, South Africa, Pakistan, and most likely Israel) developed nuclear arms during this time. At the end of the Cold War in the early 1990s, the Russian Federation inherited the weapons of the former USSR, and along with the USA pledged to reduce their stockpile for increased international safety. Nuclear proliferation has continued, though, with Pakistan testing their first weapons in 1998, and the state of North Korea claiming to have developed nuclear weapons in 2004. Nuclear weapons have been at the heart of many national and international political disputes, and have played a major part in popular culture since their dramatic public debut in the 1940s, and have usually symbolized the ultimate ability of mankind to utilize the strength of nature for destruction. There have been (at least) four major false alarms, the most recent in 1995, that almost resulted in the US or USSR/Russia launching its weapons in retaliation for a supposed attack.[http://www.pbs.org/wgbh/nova/missileers/falsealarms.html] Additionally, during the Cold War the US and USSR came close to nuclear warfare a number of times, most notably during the Cuban Missile Crisis. As of 2005, there are estimated to be at least 29,000 nuclear weapons held by at least seven countries, though 96% of these are in the possession of just two (the United States and the Russian Federation)

Media

References

- p. 54. Bethe, Hans Albrecht. The Road from Los Alamos. Simon and Schuster, New York. (1991 ISBN 0-671-74012-1)
- Glasstone, Samuel and Dolan, Philip J., [http://www.cddc.vt.edu/host/atomic/nukeffct/ The Effects of Nuclear Weapons (third edition)], U.S. Government Printing Office, 1977. [http://www.princeton.edu/~globsec/publications/effects/effects.shtml PDF Version]
- [http://www.fas.org/nuke/guide/usa/doctrine/dod/fm8-9/1toc.htm NATO Handbook on the Medical Aspects of NBC Defensive Operations (Part I - Nuclear)], Departments of the Army, Navy, and Air Force, Washington, D.C., 1996.
- Hansen, Chuck. U.S. Nuclear Weapons: The Secret History, Arlington, TX: Aerofax, 1988.
- Hansen, Chuck. The Swords of Armageddon: U.S. nuclear weapons development since 1945, Sunnyvale, CA: Chukelea Publications, 1995 [http://www.uscoldwar.com/].
- Smyth, Henry DeWolf. [http://nuclearweaponarchive.org/Smyth/ Atomic Energy for Military Purposes], Princeton University Press, 1945. (The first declassified report by the US government on nuclear weapons) (Smyth Report)
- [http://www.fas.org/nuke/intro/nuke/7906/index.html The Effects of Nuclear War], Office of Technology Assessment (May 1979).
- Rhodes, Richard. Dark Sun: The Making of the Hydrogen Bomb. Simon and Schuster, New York, (1995 ISBN 0684824140)
- Rhodes, Richard. The Making of the Atomic Bomb. Simon and Schuster, New York, (1986 ISBN 0684813785)
- Weart, Spencer R. Nuclear Fear: A History of Images. Cambridge, Mass.: Harvard University Press, 1988.

External links

- [http://intergate.cccoe.k12.ca.us/abomb/ "The Race to Build the Atomic Bomb"] educational resource
- [http://nuclearweaponarchive.org Nuclear Weapon Archive from Carey Sublette] is a reliable source of information and has links to other sources and an informative [http://nuclearweaponarchive.org/Nwfaq/Nfaq0.html FAQ].
- [http://www.fas.org/main/content.jsp?formAction=297&contentId=367 Nuclear weapon simulator for several major cities]
- [http://www.fas.org/main/content.jsp?formAction=297&contentId=409 Fallout Calculator for various regions]
- [http://www.neis.org/literature/Brochures/weapcon.htm "Nuclear Power and Nuclear Weapons: Making the Connections"] – an article about the connections between nuclear power and nuclear weapons development by an anti-nuclear group
- The [http://fas.org Federation of American Scientists] provide solid information on weapons of mass destruction, including [http://fas.org/nuke/ nuclear weapons] and their [http://www.fas.org/nuke/intro/nuke/effects.htm effects]
- [http://www.oism.org/nwss/ Nuclear War Survival Skills] is a public domain text about civil defense.
- [http://www.atomicarchive.com/Example/Example1.shtml Step by step scenario of a 150 kiloton bomb exploding in Manhattan] - click on the Next >> button at the bottom of each slide.
- [http://www.ippnw.org IPPNW: International Physicians for the Prevention of Nuclear War] Nobel Peace Prize-winning organization with information about the medical consequences of nuclear weapons, war and militarization.
- [http://www.thebulletin.org Bulletin of the Atomic Scientists] - Magazine founded in 1945 by Manhattan Project scientists. Covers nuclear weapons proliferation and many other global security issues. See [http://www.thebulletin.org/nuclear_weapons_data this page] for comprehensive data on nuclear weapons worldwide.
- [http://alsos.wlu.edu/ Alsos Digital Library for Nuclear Issues] – contains many resources related to nuclear weapons, including a historical and technical overview and searchable bibliography of web and print resources. ko:핵무기 ms:Senjata nuklear ja:核兵器 simple:Nuclear weapon th:อาวุธนิวเคลียร์

Explosive material

:This article is concerned solely with chemical explosives. There are many other varieties of more exotic explosive material, and theoretical methods of causing explosions such as nuclear explosives and antimatter, and other methods of producing explosions, such as abrupt heating with a high-intensity laser or electric arc. Any explosive material has the following characteristics:
- It is chemically or otherwise energetically unstable.
- The initiation produces a sudden expansion of the material accompanied by the production of heat and large changes in pressure (and typically also a flash or loud noise) which is called the explosion.

Chemical explosives

Explosives are classified as low or high explosives according to their rates of decomposition. Low explosives burn rapidly (or deflagrate). High explosives undergo detonation. There is no sharp line of demarcation between low and high explosives, due to the difficulties inherent in precisely observing and measuring rapid decomposition. The chemical decomposition of an explosive may take years, days, hours, or a fraction of a second. The slower forms of decomposition take place in storage and are of interest only from a stability standpoint. Of more interest are the two rapid forms of decomposition, burning and detonation. The term "detonation" is used to describe an explosive phenomenon whereby the decomposition is propagated by the explosive shockwave penetrating the explosive material. The shockwave front is capable of passing through the high explosive material at massive speeds. Explosive force is released at 90 degree angles from the surface of an explosive. If the surface is cut or shaped the explosive forces can be focused directionally, and will produce a greater effect. This is known as a shaped charge. In a low explosive, the decomposition is propagated by a flame front which travels much slower through the explosive material. The properties of the explosive indicate the class into which it falls. In some cases explosives may be made to fall into either class by the conditions under which they are initiated. Almost all low explosives can undergo true detonation like high explosives in sufficiently massive quantities. For convenience, low and high explosives may be differentiated by the shipping and storage classes.

Explosive compatibility groupings

differentiated Shipping tags will include a UN or US DOT hazardous material class with compatibility letter as follows.
- 1.1 Mass Explosion Hazard
- 1.2 Nonmass explosion, fragment-producing
- 1.3 Mass fire, minor blast or fragment hazard
- 1.4 Moderate fire, no blast or fragment: consumer fireworks are 1.4G or 1.4S
- 1.5 Explosive substance, very insensitive (with a mass explosion hazard)
- 1.6 Explosive article, extremely insensitive A Primary explosive substance (1.1A, 1.2A) B An article containing a primary explosive substance and not containing two or more effective protective features. Some articles, such as detonator assemblies for blasting and primers, cap-type, are included. (1.1B, 1.2B, 1.4B) C Propellant explosive substance or other deflagrating explosive substance or article containing such explosive substance (1.1C, 1.2C, 1.3C, 1.4C) D Secondary detonating explosive substance or black powder or article containing a secondary detonating explosive substance, in each case without means of initiation and without a propelling charge, or article containing a primary explosive substance and containing two or more effective protective features. (1.1D, 1.2D, 1.4D, 1.5D) E Article containing a secondary detonating explosive substance without means of initiation, with a propelling charge (other than one containing flammable liquid, gel or hypergolic liquid) (1.1E, 1.2E, 1.4E) F Article containing a secondary detonating explosive substance with its means of initiation, with a propelling charge (other than one containing flammable liquid, gel or hypergolic liquid) or without a propelling charge (1.1F, 1.2F, 1.3F, 1.4F) G Pyrotechnic substance or article containing a pyrotechnic substance, or article containing both an explosive substance and an illuminating, incendiary, tear-producing or smoke-producing substance (other than a water-activated article or one containing white phosphorus, phosphide or flammable liquid or gel or hypergolic liquid) (1.1G, 1.2G, 1.3G, 1.4G) H Article containing both an explosive substance and white phosphorus (1.2H, 1.3H) J Article containing both an explosive substance and flammable liquid or gel (1.1J, 1.2J, 1.3J) K Article containing both an explosive substance and a toxic chemical agent (1.2K, 1.3K) L Explosive substance or article containing an explosive substance and presenting a special risk (e.g., due to water-activation or presence of hypergolic liquids, phosphides or pyrophoric substances) needing isolation of each type (1.1L, 1.2L, 1.3L) N Articles containing only extremely insensitive detonating substances (1.6N) S Substance or article so packed or designed that any hazardous effects arising from accidental functioning are limited to the extent that they do not significantly hinder or prohibit fire fighting or other emergency response efforts in the immediate vicinity of the package (1.4S)

Low Explosives

Low explosives are normally employed as propellants. Most low explosives are mixtures; most high explosives are compounds, but to both there are notable exceptions. They undergo deflagration at rates that vary from a few centimeters per second to approximately 400 meters per second. Included in this group are smokeless powders, and pyrotechnics such as flares and illumination devices.

High Explosives

High explosives are normally employed in mining, demolitions and military warheads. They undergo detonation at rates of 1,000 to 8,500 meters per second. High explosives are conventionally subdivided into two classes and differentiated by sensitivity:
- Primary explosives are extremely sensitive to shock, friction, and heat. They will burn rapidly or detonate if ignited.
- Secondary or Base explosives are relatively insensitive to shock, friction, and heat. They may burn when ignited in small, unconfined quantities, but detonation can occur. These are sometimes added in small amount to blasting caps to boost their power. Dynamite, RDX, PETN, HMX, and others are secondary explosives. Some definitions add a third category:
- Tertiary, also called blasting agents. These are so insensitive to shock that they cannot be detonated by practical quantities of primary explosive, and instead require an intermediate explosive booster of secondary explosive. Some examples would be an Ammonium Nitrate/Fuel Oil mixture commonly known as ANFO and slurry or 'Wet Bag' explosives. These are primarily used in large scale mining and construction operations. Note that many if not most explosive chemical compounds may usefully deflagrate as well as detonate, and are used in high as well as low explosive compositions. This also means that under extreme conditions, propellant can detonate. For example, nitrocellulose deflagrates if ignited, but detonates if initiated by a detonator.

Detonation of an Explosive Charge

Also called an initiation sequence or a firing train, this is the sequence of events which cascade from relatively low levels of energy to cause a chain reaction to initiate the final explosive material or main charge. They can be either low or high explosive trains. Low explosive trains are something like a bullet - Primer and a propellant charge. High explosives trains can be more complex, either Two-Step (e.g. Detonator and Dynamite) or Three-Step (e.g. Detonator, Booster and ANFO). Detonators are often made from tetryl and Fulminates.

Composition of the material

Mixtures of an oxidizer and a fuel
- Black powder: potassium nitrate, charcoal and sulfur
- Flash powder: fine metal powder (usually aluminium or magnesium) and a strong oxidizer (e.g. potassium chlorate or perchlorate).
- Ammonal: ammonium nitrate and aluminium powder.
- Armstrong's mixture: potassium chlorate and red phosphorus. This is a very sensitive mixture. It is a primary high explosive in which sulfur is substitute for some or all phosphorus to slightly decrease sensitivity.
- Sprengel explosives: a very general class incorporating any strong oxidizer and highly reactive fuel, although in practice the name most commonly was applied to mixtures of chlorates and nitroaromatics
- ANFO: ammonium nitrate and fuel oil.
- Cheddites: chlorates or perchlorates and oil
- oxyliquits: mixtures of organic materials and liquid oxygen Chemically pure compounds
- Nitroglycerin: an unstable liquid known as dynamite when mixed into sawdust, powdered silica or most commonly diatomaceous earth, which act as stabilizers.
- Acetone peroxide: A very unstable white organic peroxide
- TNT: Yellow insensitive crystals that can be melted and molded without detonation.
- Nitrocellulose: A variantly nitrated polymer which can be a high or low explosive depending on nitration level and conditions.
- RDX, PETN: Very strong explosives which can be used pure or in plastic explosives.
- C4: An RDX plastic explosive plasticized to be adhesive and malleable.

Chemical explosive reaction

A chemical explosive is a compound or mixture which, upon the application of heat or shock, decomposes or rearranges with extreme rapidity, yielding much gas and heat. Many substances not ordinarily classed as explosives may do one, or even two, of these things. For example, a mixture of nitrogen and oxygen can be made to react with great rapidity and yield the gaseous product nitric oxide; yet the mixture is not an explosive since it does not evolve heat, but rather absorbs heat. :N₂ + O₂ → 2NO - 43,200 calories (or 180 kJ) per mole of N₂ For a chemical to be an explosive, it must exhibit all of the following:
- Exhibit Rapid Expansion (eg. rapid production of gasses or rapid heating of surroundings)
- Evolution of heat
- Rapidity of reaction
- Initiation of reaction

Formation of gases

Gases may be evolved from substances in a variety of ways. When wood or coal is burned in the atmosphere, the carbon and hydrogen in the fuel combine with the oxygen in the atmosphere to form carbon dioxide and steam, together with flame and smoke. When the wood or coal is pulverized, so that the total surface in contact with the oxygen is increased, and burned in a furnace or forge where more air can be supplied, the burning can be made more rapid and the combustion more complete. When the wood or coal is immersed in liquid oxygen or suspended in air in the form of dust, the burning takes place with explosive violence. In each case, the same action occurs: a burning combustible forms a gas.

Evolution of heat

The generation of heat in large quantities accompanies every explosive chemical reaction. It is this rapid liberation of heat that causes the gaseous products of reaction to expand and generate high pressures. This rapid generation of high pressures of the released gas constitutes the explosion. It should be noted that the liberation of heat with insufficient rapidity will not cause an explosion. For example, although a pound of coal yields five times as much heat as a pound of nitroglycerin, the coal cannot be used as an explosive because the rate at which it yields this heat is quite slow.

Rapidity of reaction

Rapidity of reaction distinguishes the explosive reaction from an ordinary combustion reaction by the great speed with which it takes place. Unless the reaction occurs rapidly, the thermally expanded gases will be dissipated in the medium, and there will be no explosion. Again, consider a wood or coal fire. As the fire burns, there is the evolution of heat and the formation of gases, but neither is liberated rapidly enough to cause an explosion. For those who know something about electronics, this can be likened to the energy discharge of a battery, which is slow; to a flash capacitor, like that in a camera flash and releases its energy all at once.

Initiation of reaction

A reaction must be capable of being initiated by the application of shock or heat to a small portion of the mass of the explosive material. A material in which the first three factors exist cannot be accepted as an explosive unless the reaction can be made to occur when desired.

Military explosives

To determine the suitability of an explosive substance for military use, its physical properties must first be investigated. The usefulness of a military explosive can only be appreciated when these properties and the factors affecting them are fully understood. Many explosives have been studied in past years to determine their suitability for military use and most have been found wanting. Several of those found acceptable have displayed certain characteristics that are considered undesirable and, therefore, limit their usefulness in military applications. The requirements of a military explosive are stringent, and very few explosives display all of the characteristics necessary to make them acceptable for military standardization. Some of the more important characteristics are discussed below:

Availability and cost

In view of the enormous quantity demands of modern warfare, explosives must be produced from cheap raw materials that are nonstrategic and available in great quantity. In addition, manufacturing operations must be reasonably simple, cheap, and safe.

Sensitivity

Regarding an explosive, this refers to the ease with which it can be ignited or detonated—i.e., the amount and intensity of shock, friction, or heat that is required. When the term sensitivity is used, care must be taken to clarify what kind of sensitivity is under discussion. The relative sensitivity of a given explosive to impact may vary greatly from its sensitivity to friction or heat. Some of the test methods used to determine sensitivity are as follows:
- Impact Sensitivity is expressed in terms of the distance through which a standard weight must be dropped to cause the material to explode.
- Friction Sensitivity is expressed in terms of what occurs when a weighted pendulum scrapes across the material (snaps, crackles, ignites, and/or explodes).
- Heat Sensitivity is expressed in terms of the temperature at which flashing or explosion of the material occurs. Sensitivity is an important consideration in selecting an explosive for a particular purpose. The explosive in an armor-piercing projectile must be relatively insensitive, or the shock of impact would cause it to detonate before it penetrated to the point desired.

Stability

Stability is the ability of an explosive to be stored without deterioration. The following factors affect the stability of an explosive:
- Chemical constitution. The very fact that some common chemical compounds can undergo explosion when heated indicates that there is something unstable in their structures. While no precise explanation has been developed for this, it is generally recognized that certain groups, nitro dioxide (NO₂), nitrate (NO₃), and azide (N₃), are intrinsically in a condition of internal strain. Increased strain through heating can cause a sudden disruption of the molecule and consequent explosion. In some cases, this condition of molecular instability is so great that decomposition takes place at ordinary temperatures.
- Temperature of storage. The rate of decomposition of explosives increases at higher temperatures. All of the standard military explosives may be considered to be of a high order of stability at temperatures of -10 to +35 °C, but each has a high temperature at which the rate of decomposition becomes rapidly accelerated and stability is reduced. As a rule of thumb, most explosives become dangerously unstable at temperatures exceeding 70 °C.
- Exposure to sun. If exposed to the ultraviolet rays of the sun, many explosive compounds that contain nitrogen groups will rapidly decompose, affecting their stability.
- Electrical discharge. Electrostatic or spark sensitivity to initiation is common to a number of explosives. Static or other electrical discharge may be sufficient to inspire detonation under some circumstances. As a result, the safe handling of explosives and pyrotechnics almost always requires electrical grounding of the operator.

Power

The term power (or more properly, performance) as it is applied to an explosive refers to its ability to do work. In practice it is defined as its ability to accomplish what is intended in the way of energy delivery (i.e., fragments, air blast, high-velocity jets, underwater bubble energy, etc.). Explosive power or performance is evaluated by a tailored series of tests to assess the material for its intended use. Of the tests listed below, cylinder expansion and air-blast tests are common to most testing programs, and the others support specific uses.
- Cylinder expansion test. A standard amount of explosive is loaded in a cylinder usually manufactured of copper. Data is collected concerning the rate of radial expansion of the cylinder and maximum cylinder wall velocity. This also establishes the Gurney constant or 2E.
- Cylinder fragmentation test. A standard steel cylinder is charged with explosive and fired in a sawdust pit. The fragments are collected and the size distribution analyzed.
- Detonation pressure (Chapman-Jouget). Detonation pressure data derived from measurements of shock waves transmitted into water by the detonation of cylindrical explosive charges of a standard size.
- Determination of critical diameter. This test establishes the minimum physical size a charge of a specific explosive must be to sustain its own detonation wave. The procedure involves the detonation of a series of charges of different diameters until difficulty in detonation wave propagation is observed.
- Infinity diameter detonation velocity. Detonation velocity is dependent on landing density (c), charge diameter, and grain size. The hydrodynamic theory of detonation used in predicting explosive phenomena does not include diameter of the charge, and therefore a detonation velocity, for an imaginary charge of infinite diameter. This procedure requires a series of charges of the same density and physical structure, but different diameters, to be fired and the resulting detonation velocities extrapolated to predict the detonation velocity of a charge of infinite diameter.
- Pressure versus scaled distance. A charge of specific size is detonated and its pressure effects measured at a standard distance. The values obtained are compared with that for TNT.
- Impulse versus scaled distance. A charge of specific size is detonated and its impulse (the area under the pressure-time curve) measured versus distance. The results are tabulated and expressed in TNT equivalent.
- Relative bubble energy (RBE). A 5 to 50 kg charge is detonated in water and piezoelectric gauges are used to measure peak pressure, time constant, impulse, and energy. ::The RBE may be defined as K_x 3 ::RBE = K_s ::where K = bubble expansion period for experimental (x) or standard (s) charge.

Brisance

In addition to strength, explosives display a second characteristic, which is their shattering effect or brisance (from the French meaning to "break"), which is distinguished from their total work capacity. This characteristic is of practical importance in determining the effectiveness of an explosion in fragmenting shells, bomb casings, grenades, and the like. The rapidity with which an explosive reaches its peak pressure is a measure of its brisance. Brisance values are primarily employed in France and Russia. The sand crush test is commonly employed to determine the relative brisance in comparison to TNT. No single test is capable of directly comparing the explosive properties of two or more compounds; it is important to examine the data from several such tests (sand crush, trauzl, and so forth) in order to gauge relative brisance. True values for comparison will require field experiments.

Density

Density of loading refers to the unit weight of an explosive per unit volume. Several methods of loading are available, and the one used is determined by the characteristics of the explosive. The methods available include pellet loading, cast loading, or press loading. Dependent upon the method employed, an average density of the loaded charge can be obtained that is within 80-95% of the theoretical maximum density of the explosive. High load density can reduce sensitivity by making the mass more resistant to internal friction. If density is increased to the extent that individual crystals are crushed, the explosive will become more sensitive. Increased load density also permits the use of more explosive, thereby increasing the strength of the warhead.

Volatility

Volatility, or the readiness with which a substance vaporizes, is an undesirable characteristic in military explosives. Explosives must be no more than slightly volatile at the temperature at which they are loaded or at their highest storage temperature. Excessive volatility often results in the development of pressure within rounds of ammunition and separation of mixtures into their constituents. Stability, as mentioned before, is the ability of an explosive to stand up under storage conditions without deteriorating. Volatility affects the chemical composition of the explosive such that a marked reduction in stability may occur, which results in an increase in the danger of handling. Maximum allowable volatility is 2 ml of gas evolved in 48 hours.

Hygroscopicity

The introduction of moisture into an explosive is highly undesirable since it reduces the sensitivity, strength, and velocity of detonation of the explosive. Hygroscopicity is used as a measure of a material's moisture-absorbing tendencies. Moisture affects explosives adversely by acting as an inert material that absorbs heat when vaporized, and by acting as a solvent medium that can cause undesired chemical reactions. Sensitivity, strength, and velocity of detonation are reduced by inert materials that reduce the continuity of the explosive mass. When the moisture content evaporates during detonation, cooling occurs, which reduces the temperature of reaction. Stability is also affected by the presence of moisture since moisture promotes decomposition of the explosive and, in addition, causes corrosion of the explosive's metal container. For all of these reasons, hygroscopicity must be negligible in military explosives.

Toxicity

Due to their chemical structure, most explosives are toxic to some extent. Since the effect of toxicity may vary from a mild headache to serious damage of internal organs, care must be taken to limit toxicity in military explosives to a minimum. Any explosive of high toxicity is unacceptable for military use.

Measurement of chemical explosive reaction

The development of new and improved types of ammunition requires a continuous program of research and development. Adoption of an explosive for a particular use is based upon both proving ground and service tests. Before these tests, however, preliminary estimates of the characteristics of the explosive are made. The principles of thermochemistry are applied for this process. Thermochemistry is concerned with the changes in internal energy, principally as heat, in chemical reactions. An explosion consists of a series of reactions, highly exothermic, involving decomposition of the ingredients and recombination to form the products of explosion. Energy changes in explosive reactions are calculated either from known chemical laws or by analysis of the products. For most common reactions, tables based on previous investigations permit rapid calculation of energy changes. Products of an explosive remaining in a closed calorimetric bomb (a constant-volume explosion) after cooling the bomb back to room temperature and pressure are rarely those present at the instant of maximum temperature and pressure. Since only the final products may be analyzed conveniently, indirect or theoretical methods are often used to determine the maximum temperature and pressure values. Some of the important characteristics of an explosive that can be determined by such theoretical computations are:
- Oxygen balance
- Heat of explosion or reaction
- Volume of products of explosion
- Potential of the explosive

Oxygen balance (OB%)

Oxygen balance is an expression that is used to indicate the degree to which an explosive can be oxidized. If an explosive molecule contains just enough oxygen to convert all of its carbon to carbon dioxide, all of its hydrogen to water, and all of its metal to metal oxide with no excess, the molecule is said to have a zero oxygen balance. The molecule is said to have a positive oxygen balance if it contains more oxygen than is needed and a negative oxygen balance if it contains less oxygen than is needed. The sensitivity, strength, and brisance of an explosive are all somewhat dependent upon oxygen balance and tend to approach their maximums as oxygen balance approaches zero. The oxygen balance (OB) is calculated from the empirical formula of a compound in percentage of oxygen required for complete conversion of carbon to carbon dioxide, hydrogen to water, and metal to metal oxide. The procedure for calculating oxygen balance in terms of 100 grams of the explosive material is to determine the number of moles of oxygen that are excess or deficient for 100 grams of a compound. :

OB% = \frac \times (2X + (Y/2) + M - Z)

where X = number of atoms of carbon, Y = number of atoms of hydrogen, Z = number of atoms of oxygen, and M = number of atoms of metal (metallic oxide produced). In the case of TNT (C₆H₂(NO₂)₃CH₃), Molecular weight = 227.1 X = 7 (number of carbon atoms) Y = 5 (number of hydrogen atoms) Z = 6 (number of oxygen atoms) Therefore :

OB% = \frac \times (14 + 2.5 - 6)

:OB% = -74% for TNT Because sensitivity, brisance, and strength are properties resulting from a complex explosive chemical reaction, a simple relationship such as oxygen balance cannot be depended upon to yield universally consistent results. When using oxygen balance to predict properties of one explosive relative to another, it is to be expected that one with an oxygen balance closer to zero will be the more brisant, powerful, and sensitive; however, many exceptions to this rule do exist. More complicated predictive calculations, such as those discussed in the next section, result in more accurate predictions. One area in which oxygen balance can be applied is in the processing of mixtures of explosives. The family of explosives called amatols are mixtures of ammonium nitrate and TNT. Ammonium nitrate has an oxygen balance of +20% and TNT has an oxygen balance of −74%, so it would appear that the mixture yielding an oxygen balance of zero would also result in the best explosive properties. In actual practice a mixture of 80% ammonium nitrate and 20% TNT by weight yields an oxygen balance of +1%, the best properties of all mixtures, and an increase in strength of 30% over TNT.

Heat of explosion

When a chemical compound is formed from its constituents, the reaction may either absorb or give off heat. The quantity of heat absorbed or given off during transformation is called the heat of formation. The heats of formations for solids and gases found in explosive reactions have been determined for a temperature of 15 °C and atmospheric pressure, and are normally tabulated in units of kilocalories per gram molecule. (See table 12-1). Where a negative value is given, it indicates that heat is absorbed during the formation of the compound from its elements. Such a reaction is called an endothermic reaction. The convention usually employed in simple thermochemical calculations is arbitrarily to take heat contents of all elements as zero in their standard states at all temperatures (standard state being defined as the state at which the elements are found under natural or ambient conditions). Since the heat of formation of a compound is the net difference between the heat content of the compound and that of its elements, and since the latter are taken as zero by convention, it follows that the heat content of a compound is equal to its heat of formation in such nonrigorous calculations. This leads us to the principle of initial and final state, which may be expressed as follows: "The net quantity of heat liberated or absorbed in any chemical modification of a system depends solely upon the initial and final states of the system, provided the transformation takes place at constant volume or at constant pressure. It is completely independent of the intermediate transformations and of the time required for the reactions." From this it follows that the heat liberated in any transformation accomplished through successive reactions is the algebraic sum of the heats liberated or absorbed in the different reactions. Consider the formation of the original explosive from its elements as an intermediate reaction in the formation of the products of explosion. The net amount of heat liberated during an explosion is the sum of the heats of formation of the products of explosion, minus the heat of formation of the original explosive. The net heat difference between heats of formations of the reactants and products in a chemical reaction is termed the heat of reaction. For oxidation this heat of reaction may be termed heat of combustion. In explosive technology only materials that are exothermic — that is, have a heat of reaction that causes net liberation of heat — are of interest. Hence, in this text, heats of reaction are virtually all positive. Reaction heat is measured under conditions either of constant pressure or constant volume. It is this heat of reaction that may be properly expressed as "heat of the explosion."

Balancing chemical explosion equations

In order to assist in balancing chemical equations, an order of priorities is presented in table 12-2. Explosives containing C, H, O, and N and/or a metal will form the products of reaction in the priority sequence shown. Some observation you might want to make as you balance an equation:
- The progression is from top to bottom; you may skip steps that are not applicable, but you never back up.
- At each separate step there are never more than two compositions and two products.
- At the conclusion of the balancing, elemental forms, nitrogen, oxygen, and hydrogen, are always found in diatomic form. Example, TNT: :C₆H₂(NO₂)₃CH₃; constituents: 7C + 5H + 3N + 6O Using the order of priorities in table 12-1, priority 4 gives the first reaction products: :7C + 6O → 6CO with one mol of carbon remaining Next, since all the oxygen has been combined with the carbon to form CO, priority 7 results in: :3N → 1.5N₂ Finally, priority 9 results in: 5H → 2.5H₂ The balanced equation, showing the products of reaction resulting from the detonation of TNT is: :C₆H₂(NO₂)₃CH₃ → 6CO + 2.5H₂ + 1.5N₂ + C Notice that partial moles are permitted in these calculations. The number of moles of gas formed is 10. The product, carbon, is a solid.

Volume of products of explosion

The law of Avogadro states that equal volumes of all gases under the same conditions of temperature and pressure contain the same number of molecules. From this law, it follows that the molar volume of one gas is equal to the molar volume of any other gas. The molar volume of any gas at 0 °C and under normal atmospheric pressure is very nearly 22.4 liters or 22.4 cubic decimeters. Thus, considering the nitroglycerin reaction. :C₃H₅(NO₃)₃ → 3CO₂ + 2.5H₂O + 1.5N₂ + 0.25O₂ the explosion of one mole of nitroglycerin produces in the gaseous state: 3 moles of CO₂; 2.5 moles of O₂. Since a molar volume is the volume of one mole of gas, one mole of nitroglycerin produces 3 + 2.5 + 1.5 + 0.25 = 7.25 molar volumes of gas; and these molar volumes at 0 °C and atmospheric pressure form an actual volume of 7.25 × 22.4 = 162.4 liters of gas. (Note that the products H₂O and CO₂ are in their gaseous form.) Based upon this simple beginning, it can be seen that the volume of the products of explosion can be predicted for any quantity of the explosive. Further, by employing Charles' Law for perfect gases, the volume of the products of explosion may also be calculated for any given temperature. This law states that at a constant pressure a perfect gas expands 1/273.15 of its volume at 0 °C, for each degree Celsius of rise in temperature. Therefore, at 15 °C the molar volume of an ideal gas is, :V₁₅ = 22.414 (288.15/273.15) = 23.64 liters per mole Thus, at 15 °C the volume of gas produced by the explosive decomposition of one mole of nitroglycerin becomes :V = (23.64 l/mol)(7.25 mol) = 171.4 l

Explosive strength

The potential of an explosive is the total work that can be performed by the gas resulting from its explosion, when expanded adiabatically from its original volume, until its pressure is reduced to atmospheric pressure and its temperature to 15 °C. The potential is therefore the total quantity of heat given off at constant volume when expressed in equivalent work units and is a measure of the strength of the explosive. An explosion may occur under two general conditions: the first, unconfined, as in the open air where the pressure (atmospheric) is constant; the second, confined, as in a closed chamber where the volume is constant. The same amount of heat energy is liberated in each case, but in the unconfined explosion, a certain amount is used as work energy in pushing back the surrounding air, and therefore is lost as heat. In a confined explosion, where the explosive volume is small (such as occurs in the powder chamber of a firearm), practically all the heat of explosion is conserved as useful energy. If the quantity of heat liberated at constant volume under adiabatic conditions is calculated and converted from heat units to equivalent work units, the potential or capacity for work results. Therefore, if Q_mp represents the total quantity of heat given off by a mole of explosive of 15 °C and constant pressure (atmospheric); Q_mv represents the total heat given off by a mole of explosive at 15 °C and constant volume; and W represents the work energy expended in pushing back the surrounding air in an unconfined explosion and thus is not available as net theoretical heat; Then, because of the conversion of energy to work in the constant pressure case, :Q_mv = Q_mp + W from which the value of Q_mv may be determined. Subsequently, the potential of a mole of an explosive may be calculated. Using this value, the potential for any other weight of explosive may be determined by simple proportion. Using the principle of the initial and final state, and heat of formation table (resulting from experimental data), the heat released at constant pressure may be readily calculated. m n Q_mp = v_iQ_fi - v_kQ_fk 1 1 where: Q_fi = heat of formation of product i at constant pressure Q_fk = heat of formation of reactant k at constant pressure v = number of moles of each product/reactants (m is the number of products and n the number of reactants) The work energy expended by the gaseous products of detonation is expressed by: :W = P dv With pressure constant and negligible initial volume, this expression reduces to: :W = P·V₂ Since heats of formation are calculated for standard atmospheric pressure (101 325 Pa, where 1 Pa = 1 N/m²) and 15 °C, V₂ is the volume occupied by the product gases under these conditions. At this point W/mol = (101 325 N/m²)(23.63 L/mol)(1 m³/1000 L) = 2394 N·m/mol = 2394 J/mol and by applying the appropriate conversion factors, work can be converted to units of kilocalories. W/mol = 0.572 kcal/mol Once the chemical reaction has been balanced, one can calculate the volume of gas produced and the work of expansion. With this completed, the calculations necessary to determine potential may be accomplished. For TNT: :C₆H₂(NO₂)₃CH₃ → 6CO + 2.5H₂ + 1.5N₂ + C for 10 mol Then: :Q_mp = 6(26.43) - 16.5 = 142.08 kcal/mol Note: Elements in their natural state (H₂, O₂, N₂, C, etc.) are used as the basis for heat of formation tables and are assigned a value of zero. See table 12-2. :Q_mv = 142.08 + 0.572(10) = 147.8 kcal/mol As previously stated, Q_mv converted to equivalent work units is the potential of the explosive. (MW = Molecular Weight of Explosive) Potential = Q_mv kcal/mol × 4185 J/kcal × 10³ g/kg × 1 mol/(mol·g) Potential = Q_mv (4.185 × 10⁶) J/(mol·kg) For TNT, Potential = 147.8 (4.185 × 10⁶)/227.1 = 2.72 × 10⁶ J/kg Rather than tabulate such large numbers, in the field of explosives, TNT is taken as the standard explosive, and others are assigned strengths relative to that of TNT. The potential of TNT has been calculated above to be 2.72 × 10⁶ J/kg. Relative strength (RS) may be expressed as :R.S. = Potential of Explosive/(2.72 × 10⁶)

Example of thermochemical calculations

The PETN reaction will be examined as an example of thermo-chemical calculations. :PETN: C(CH₂ONO₂)₄ :Molecular weight = 316.15 g/mol :Heat of formation = 119.4 kcal/mol (1) Balance the chemical reaction equation. Using table 12-1, priority 4 gives the first reaction products: :5C + 12O → 5CO + 7O Next, the hydrogen combines with remaining oxygen: :8H + 7O → 4H₂O + 3O Then the remaining oxygen will combine with the CO to form CO and CO₂. :5CO + 3O → 2CO + 3CO₂ Finally the remaining nitrogen forms in its natural state (N₂). :4N → 2N₂ The balanced reaction equation is: :C(CH₂ONO₂)₄ → 2CO + 4H₂O + 3CO₂ + 2N₂ (2) Determine the number of molar volumes of gas per mole. Since the molar volume of one gas is equal to the molar volume of any other gas, and since all the products of the PETN reaction are gaseous, the resulting number of molar volumes of gas (N_m) is: :N_m = 2 + 4 + 3 + 2 = 11 V_molar/mol (3) Determine the potential (capacity for doing work). If the total heat liberated by an explosive under constant volume conditions (Q_m) is converted to the equivalent work units, the result is the potential of that explosive. The heat liberated at constant volume (Q_mv) is equivalent to the liberated at constant pressure (Q_mp) plus that heat converted to work in expanding the surrounding medium. Hence, Q_mv = Q_mp + work (converted). :a. Q_mp = Q_fi (products) - Q_fk (reactants) ::where: Q_f = heat of formation (see table 12-2) ::For the PETN reaction: :::Q_mp = 2(26.343) + 4(57.81) + 3(94.39) - (119.4) = 447.87 kcal/mol ::(If the compound produced a metallic oxide, that heat of formation would be included in Q_mp. :b. Work = 0.572N_m = 0.572(11) = 6.292 kcal/mol :As previously stated, Q_mv converted to equivalent work units is taken as the potential of the explosive. :c. Potential J = Q_mv (4.185 × 10⁶ kg)(MW) = 454.16 (4.185 × 10⁶) 316.15 = 6.01 × 10⁶ J kg :This product may then be used to find the relative strength (RS) of PETN, which is :d. RS = Pot (PETN) = 6.01 × 10⁶ = 2.21 Pot (TNT) 2.72 × 10⁶

External links

- [http://www.blasterexchange.com Blaster Exchange - Explosives Industry Portal]
- [http://www.fas.org/man/dod-101/navy/docs/fun/part12.htm Military Explosives]
- [http://globalsecurity.org/military/systems/munitions/explosives-class.htm UN hazard classification code]
- [http://environmentalchemistry.com/yogi/hazmat/placards/class1.html Class 1 Hazmat Placards]

References

- Army Research Office. Elements of Armament Engineering (Part One). Washington, D.C.: U.S. Army Material Command, 1964.
- Commander, Naval Ordnance Systems Command. Safety and Performance Tests for Qualification of Explosives. NAVORD OD 44811. Washington, D.C.: GPO, 1972.
- Commander, Naval Ordnance Systems Command. Weapons Systems Fundamentals. NAVORD OP 3000, vol. 2, 1st rev. Washington, D.C.: GPO, 1971.
- Departments of the Army and Air Force. Military Explosives. Washington, D.C.: 1967.
- USDOT Hazardous Materials Transportation Placards Category:Explosives ja:火薬

Onomatopoeia

In rhetoric, linguistics and poetry, onomatopoeia is a figure of speech that employs a word, or occasionally, a grouping of words, that imitates, echoes, or suggests the object it is describing, such as "bang", "click", "fizz", "hush" or "buzz", or animal noises such as "moo", "quack" or "meow". They are also a very common feature of comic strip writing, where words such as "Pow", or "Ka-pwing" help the reader to better imagine what is being described, and make up for the lack of literary description. Onomatopoetic words exist in every language, although they are different in each. For example:-
- In Latin, tuxtax was the equivalent of "bam" or "whack" and was meant to imitate the sound of blows landing.
- In Ancient Greek, koax was used as the sound of a frog croaking.
- In Japanese, dokidoki is used to indicate the beating of a heart.
Sometimes onomatopoetic words have a very tenuous relationship with the object they describe, such as bow-wow in English and wang-wang in Chinese for the sound a dog makes.
Some animals are named after the sounds they make, especially birds such as the cuckoo and chickadee. This practice is especially common in certain languages such as Māori and therefore in names for birds borrowed from these languages.

Examples and uses of onomatopoeia

Everyday sounds

Some other very common English-language examples include:
- beep
- boing
- boom
- clap
- crackle
- hiccup
- ping pong
- plop
- poof
- thud
- tick-tock
- swoosh
- zap

Machine sounds

Aside from the above, machines are usually described with:
- automobile - "honk" for the horn, "vroom" for the engine, "screech" for the tires
- train - "clickety-clack" crossing a junction, "choo-choo" for the whistle.
- cash register - "kaching"

Animal sounds

For animal sounds, these words are typically used in English:
- bee - "buzz"
- cat - "mereow" (U.S.) / "miaow" (UK), "meow" (U.S.) / "miow" (UK), "purr", and the entire Cats Duet by Rossini
- bird - "chirp", "tweet"
- chickadee - "chickadee"
- chicken - "cluck", "cackle", "bawk,"
- crow - "caw"
- dove - "coo"
- duck - "quack"
- owl - "hoo" or "hoot"
- rooster - "cockadoodledoo"
- turkey - "gobble"
- cow - "moo"
- dog - "woof", "arf", "grrr" (see bark (dog))
- dolphin - "click"
- insects - "buzz"
- frog - "ribbit", "croak". Note: many species of frog make different calls.
- lion - "roar"
- horse - "neigh", "whinny", "snort"
- human - "prattle", "blab", "blah blah", "murmur", "brouhaha", "bar bar", "yadda yadda"
- mouse - "squeak"
- snake - "hiss"
- pig - "oink", "wee-wee-wee"
- sheep - "baa"
- wolf - "howl", "Aroo" Some of these words are used as nouns and verbs when describing the noise. See also http://www.georgetown.edu/faculty/ballc/animals/animals.html for information on animal sounds throughout the world. Note: "beep beep" for the Roadrunner was transferred from the television cartoon and is not the call that the natural bird makes.

Examples in literature

Examples in literature often strive to be more suggestive than imitative:
- "Over the cobbles he clattered and clashed in the dark innyard". Alfred Noyes The Highwayman
- "My days have crackled and gone up in smoke..." Francis Thompson The Hound of Heaven
- "And ere three shrill notes the pipe he uttered, / You heard as if a army muttered; / The muttering grew to a grumbling; / And the grumbling grew to mighty rumbling; / And out of the house the rats came tumbling." Robert Browning The Pied Piper Of Hamelin
- "The moan of doves in immemorial elms, / And murmuring of innumerable bees. Alfred Lord Tennyson

Onomatopoeia in music

Onomatopoeia-based music uses the mouth and vocal cords (that is, voice) as the primary musical instrument. A common musical tool in European and American cultures is a method of voice music, technically called a solfege. A solfege is a vocalized musical scale that is commonly known as Do-Re-Mi-Fa-Sol-La-Ti. A solfege may be sung, spoken or used in a combination. A variety of similar tools are used in voice improvisation found in scat singing of jazz, Delta blues and also rock and roll and the ska variation of reggae music (especially in the form of ska called Two Tone). Asian music, especially carnatic music employs onomatopoeia to a large extent. It should be noted that historically, some forms of onomatopoeia served as a mnemonic and a mimetic tool for musicians around the world, for example kuchi shōga, a Japanese system for pronouncing drum sounds. See Voice instrumental music. According to Dick Higgins, "Three basic types of sound poetry from the relative past come to mind immediately: folk varieties, onomatopoetic or mimetic types, and nonsense poetries. The folk roots of sound poetry may be seen in the lyrics of certain folk songs, such as the Horse Songs of the Navajos or in the Mongolian materials collected by the Sven Hedin expedition." (Primary reference: Henning Haslund-Christiansen, "The Music of the Mongols: Eastern Mongolia" 1943:New York, Da Capo Press:1971; secondary reference: [http://www.ubu.com/papers/higgins_sound.html "A Taxonomy of Sound Poetry"] by Dick Higgins, From "Precisely: Ten Eleven Twelve", 1981).

Non-auditory onomatopoeia

It is sometimes the case that an item of onomatopoeia describes a phenomenon apart from the aural. The Japanese language is especially notorious for utilizing onomatopoeia to describe soundless concepts. For instance, Japanese bara bara is an onomatopoeic form reflecting a scattered state, and is considered to be imitative without being auditory. Perhaps amusingly, shiiin in Japanese stands for the "sound" of silence. (See Japanese sound symbolism.) While almost all examples in common English usage imitate sounds, the language is not entirely devoid of non-auditory onomatopoeia. A few such words have gaining parlance recently, including bling bling, the sound of light reflecting off diamonds, and the Simpsons-inspired yoink, the sound of someone stealing something.

Onomatopoeia in advertising

Advertising uses onomatopeoia as a mnemonic so consumers will remember their products:
- Rice Krispies - "Snap, crackle, pop" when you pour on milk.
- Alka-Seltzer - makes a "plop, plop, fizz, fizz" noise when dunked in water.
- Cocoa Puffs - a wacky bird is "cuckoo" for them.
- Road safety: "clunk click, every trip" (click the seatbelt on after clunking the car door closed; UK campaign)

Onomatopoeic names

Occasionally, words for things are created from representations of the sounds these objects make. In English, for example, there is the universal fastener which is named for the onomatopoeic of the sound it makes; the zipper. As another example, young children and their parents often refer to a locomotive as a "choo-choo" A number of animals, especially birds, also get their names from the onomatopoeic link with the calls they make, such as the Chickadee, the Cuckoo, the Whooping Crane, and the Chiffchaff.

Onomatopoeias in pop culture

- The images Blam (1962) & Whaam! (1963) by Roy Lichtenstein are two of the earliest examples of pop art, featuring empty fighter aircraft being struck by rockets with dazzling red and yellow explosions.
- In Mario games, Thwomp is the sound that the big crush block makes, and is also the name of the monster. Whomp is Thwomp's brother, and WHOMP! is the onomatopia that Whomp would make. In the original Japanese, Thwomp is called Dossun, which has a similar aural connotation.
- The chorus of Kid Creole and the Coconuts' "Annie, I'm not Your Daddy", is a repetition of the word "Onomatopoeia ".
- The song "Onomatopoeia" appeared on the 1978 release "The Hermit of Mink Hollow" by Todd Rundgren and contained various examples of the title.
- In Batman, Onomatopoeias such as "WHACK" and "CRUNCH" appear on-screen when said-sounds are made during fight scenes.

External links

- [http://www.figarospeech.com/ Figures of Speech]

English language

English is a West Germanic language that is spoken in the United Kingdom, United States, Canada, Australia, New Zealand, Ireland, South Africa, and many other countries. English is now the third-most spoken native language worldwide (after Chinese and Hindi), with some 380 million speakers. It has lingua franca status in many parts of the world, due to the military, economic, scientific, political and cultural influence of the British Empire in the 18th and 19th centuries and that of the United States from the 20th century to the present. Through the global influence of native English speakers in cinema, airlines, broadcasting, science, and the Internet in recent decades, English is now the most widely learned second language in the world. Many students worldwide are required to learn some English, and a working knowledge of English is required in many fields and occupations.

History

English is a West Germanic language that originated from the Old Saxon language brought to Britain by Germanic settlers from various parts of northwest Germany. The original Old English language was subsequently influenced by two successive waves of invasion. The first was by speakers of languages in the Scandinavian branch of the Germanic family, who colonised parts of Britain in the 8th and 9th centuries. The second wave was of the Normans in the 11th century, who spoke a variety of French. These two invasions caused English to become "creolised" to some degree (though it was never a full creole in the linguistic sense of the word); creolisation arises from the cohabitation of speakers of different languages, who develop a hybrid tongue for basic communication. Cohabitation with the Scandinavians resulted in a significant grammatical simplification and lexical enrichment of the Anglo-Friesian core of English; the later Norman occupation led to the grafting onto that Germanic core a more elaborate layer of words from the Romance branch of European languages; this new layer entered English through use in the courts and government. Thus, English developed into a "borrowing" language of considerable suppleness and huge vocabulary. According to the Anglo-Saxon Chronicle, around the year 449, Vortigern, King of the British Isles, invited the "Angle kin" (Angles led by Hengest and Horsa) to help him against the Picts. In return, the Angles were granted lands in the south-east. Further aid was sought, and in response "came men of Ald Seaxum of Anglum of Iotum" (Saxons, Angles, and Jutes). The Chronicle talks of a subsequent influx of settlers who eventually established seven kingdoms, known as the heptarchy. Modern scholarship considers most of this story to be legendary and politically motivated. These Germanic invaders dominated the original Celtic-speaking inhabitants, whose languages survived largely in Scotland, Wales, Cornwall, and Ireland. The dialects spoken by the invaders formed what would be called Old English, which resembled some coastal dialects in what are now the Netherlands and north-west Germany. Later, it was strongly influenced by the North Germanic language Norse, spoken by the Vikings who settled mainly in the north-east (see Jorvik). The new and the earlier settlers spoke languages from different branches of the Germanic family; many of their lexical roots were the same or similar, although their grammars were more distant, including the prefixes, suffixes and inflections of many of their words. The Germanic language of these Old English inhabitants of Britain would be partly creolised by the contact with Norse invaders. This resulted in a stripping away of much of the grammar of Old English, including gender and case, with the notable exception of the pronouns; thus, the language became simpler and plainer. The most famous work from the Old English period is the epic poem "Beowulf", by an unknown poet. For the 300 years following the Norman Conquest in 1066, the Norman kings and the high nobility spoke only a variety of French. A large number of Norman words were assimilated into Old English, with some words doubling for Old English words (for instance, ox/beef, sheep/mutton). The Norman influence reinforced the continual evolution of the language over the following centuries, resulting in what is now referred to as Middle English. Among the changes was a broadening in the use of a unique aspect of English grammar, the "continuous" tenses, with the suffix "-ing". During the 15th century, Middle English was transformed by the Great Vowel Shift, the spread of a standardised London-based dialect in government and administration, and the standardising effect of printing. Modern English can be traced back to around the time of William Shakespeare. The most well-known work from the Middle English period is Geoffrey Chaucer's The Canterbury Tales.

Classification and related languages

The English l