A bomb is any of a range of devices that typically rely on the
exothermic chemical reactionof an explosive materialto produce an extremely sudden and violent release of energy. (A nuclear weaponemploys chemical-based explosives to initiate a much larger nuclear-based explosive reaction.) The word comes from the Greek word "βόμβος" ("bombos"), an onomatopoetic term with approximately the same meaning as "boom" in English.
The term "bomb" is not usually applied to explosive devices used for
civilianpurposes such as constructionor mining, although the people using the devices may sometimes refer to them as bombs. The military use of the term "bomb", or more specifically aerial bomb, typically refers to airdropped, unpowered explosive weapons most commonly used by air forces and naval aviation. Other military explosive devices not classified as "bombs" include grenades, shells, depth charges (used in water), warheads when in missiles, or land mines. In unconventional warfare, "bomb" can refer to any of a limitless range of explosive devices used as boobytraps or offensive weapons.
Detonationcauses destruction, injury and/or death within the blast radiusthrough three distinct yet inter-related phenomena: shock wave(a.k.a. detonation wave, pressure wave or overpressure), thermal wave and fragmentation.
A shock wave is produced when an explosive event suddenly displaces a volume of air spherically outward from the point of detonation. At its initial creation this phenomenon might best be visualized as a round, thick "shell" of highly compressed air enclosing a vacuum. This shell of pressurized air will expand outward at a speed described by the
Chapman-Jouguet condition, typically several to many times the speed of sound.
Even brief exposure to overpressure conditions can cause severe damage, crush injury and death. 1psi overpressure can shatter windows, 5psi can rupture eardrums and shatter a 12-inch concrete wall, and 15psi can cause severe lung damage. Shock waves dissipate as they expand, and the greatest defense against shock injuries is distance from the source of shock. [cite book |last= Marks |first= Michael E. |title=
The Emergency Responder's Guide to Terrorism|publisher= Red Hat Publishing Co., Inc.|year= 2002 |pages= 30 |isbn= 1-932235-00-0 ] As a point of reference, the overpressure at the Oklahoma City bombingwas estimated in the range of 4000psi. [cite article |last= Wong |first= Henry |title= Blast-Resistant Building Design Technology Analysis of its Application to Modern Hotel Design|publisher= WGA Wong Gregerson Architects, Inc.|year= 2002 |pages= 5 ]
Shock waves produced by explosive events actually have two distinct components, the positive and negative wave. The positive wave shoves outward from the point of detonation, followed by the trailing vacuum space which "sucks back" towards the point of origin as the shock bubble collapses back on itself. This is most clearly observed in footage from the
Trinity nuclear testwhere both the positive and negative effects on buildings are evident. [cite web |url=http://www.archive.org/details/Houseint1954 |title=The House in the Middle |date=1954 |publisher= Federal Civil Defense Administration|accessdate=2008-07-16]
A thermal wave is created by the sudden release of heat caused by an explosion. Military bomb tests have documented temperatures of 3000 to 4500˚F. While capable of inflicting severe to catastrophic burns and causing secondary fires, thermal wave effects are considered very limited in range compared to shock and fragmentation. This rule has been challenged, however, by military development of
thermobaric weapons, which employ a combination of negative shock wave effects and extreme temperature to incinerate objects within the blast radius.
Fragmentation is produced by the acceleration of shattered pieces of bomb casing and adjacent physical objects. This is technically distinct, although practically indistinguishable, from
shrapnel, which is physical objects, such as steel balls or nails, added to a bomb specifically to increase injury. While conventionally viewed as small metal shards moving at super- to hypersonic speeds, fragmentation can occur in epic proportions and travel for extensive distances. When the S.S. Grandcamp exploded in the Texas City Disasteron April 16, 1947, one "fragment" of that blast was a two ton anchor which was hurled nearly two miles inland to embed itself in the parking lot of the Pan American refinery.
Experts commonly distinguish between civilian 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, civilian 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, civilian-made bombs are generally referred to as
improvised explosive devices (IEDs). IEDs are divided into three basic categories by basic size and delivery. Type 1 IEDs are hand-carried parcel or suitcase bombs, type 2 are "suicide vests" worn by a bomber, and type 3 devices are vehicles laden with explosives to act as large-scale stationary or self-propelled bombs, also known as VBIED (vehicle-borne IEDs).
Improvised explosive materials are typically very unstable and subject to spontaneous, unintentional detonation triggered by a wide range of environmental effects ranging from
impactand frictionto electrostaticshock. Even subtle motion, change in temperature, or the nearby use of cellphones or radios, can trigger an unstable or remote-controlled device. Any interaction with explosive materials or devices by unqualified personnel should be considered a grave and immediate risk of death or dire injury. The safest response to finding an object believed to be an explosive device is to get as far away from it as possible.
dirty bombrefers to a specialized device that relies on a comparatively low explosive yield to scatter harmful material over a wide area. Most commonly associated with radiologicalor chemical materials, dirty bombs seek to kill or injure and then to deny access to a contaminated area until a thorough clean-up can be accomplished. In the case of urban settings, this clean-up may take extensive time, rendering the contaminated zone virtually uninhabitable in the interim.
The most powerful kind of bomb in existence is the
hydrogen bomb, a nuclear weaponwith destructive power measured in TNT equivalent. The most powerful bombs ever used in combat were the two bombs dropped by the United States to attack Hiroshimaand Nagasaki, and the most powerful ever tested was the Tsar Bomba. The most powerful non-nuclear bombs are the United States Air Force's MOAB(officially Massive Ordnance Air Blast, or more commonly known as the "Mother of All Bombs") and the Russian " Father of All Bombs". [cite web |url=http://www.reuters.com/article/worldNews/idUSL1155952320070912?feedType=RSS&feedName=worldNews&rpc=22&sp=true |title=Russia tests superstrength bomb, military says |last=Solovyov |first=Dmitry |date=2007-09-12 |publisher= Reuters|accessdate=2008-06-02]
Bombs can also be classified according to the way they are set off and radius of effect.
first air-dropped bombs were used by the Austrians in the 1849 siege of Venice. Two hundred unmanned balloons carried small bombs, few bombs actually hit Venice. [cite book |url=http://books.google.ca/books?id=7pS1QpH8FRgC&pg=PA10&dq=Venice+bombing+1849&lr=&sig=mCN924uCybWfcThJuN2nRryGtNg |title=Military Aircraft, Origins to 1918: An Illustrated History of their Impact |last=Murphy |first=Justin |coauthors=contributed by Tucker, Spencer |year=2005 |publisher= ABC-CLIO|isbn=1851094881 |pages=10 |accessdate=2008-05-26]
The first bombing from a fixed wing aircraft took place in 1911 when the Italians fought Arabs in what is now Libya. The bombs were dropped by hand. [cite book |url=http://books.google.ca/books?id=R-I3Zsdm14wC&pg=PA76&dq=Lindqvist+Bombing+Libya&lr=&sig=BZhmF-8ew2loSKwVQj30Aq9Yu9Y#PPA76,M1 |title=Shock and Awe: War on Words |chapter=Guernica |last=Lindqvist |first=Sven |others=published by Van Eekelen, Bregje |date=2004 |publisher=
North Atlantic Books|isbn=0971254605 |pages=76 |accessdate=2008-05-26]
The first significant terrorist bombing in the United States took place nine years later at noon on September 16, 1920 when a VBIED in the form of an explosives-laden horse-drawn wagon, detonated on the lunchtime-crowded streets of New York's financial district. The
Wall Street bombingemployed many aspects of modern terrorist devices, such as cast-iron slugs added for shrapnel, in a horrific attack that killed 38 and injured some 400 others.
bomberaircraft are designed around a large-capacity internal bomb baywhile fighter bombers usually carry bombs externally on pylons or bomb racks, or on multiple ejection rackswhich enable mounting several bombs on a single pylon. Modern bombs, precision-guided munitions, may be guided after they leave an aircraft by remote control, or by autonomous guidance. When bombs such as nuclear weapons are mounted on a powered platform, they are called guided missiles.
Some bombs are equipped with a
parachute, such as the World War II"parafrag", which was an 11 kg fragmentation bomb, the Vietnam-era daisy cutters, and the bomblets of some modern cluster bombs. Parachutes slow the bomb's descent, giving the dropping aircraft time to get to a safe distance from the explosion. This is especially important with airburst nuclear weapons, and in situations where the aircraft releases a bomb at low altitude.cite journal|author=Jackson, S.B. |title=The Retardation of Weapons for Low Altitude Bombing |publisher=United States Naval Institute Proceedings |date=June 1968]
hand grenadeis delivered by being thrown. Grenades can also be projected by other means using a grenade launcher, such as being launched from the muzzle of a rifleusing the M203or the GP-30or by attaching a rocketto the explosive grenade as in a rocket propelled grenade(RPG).
A bomb may also be positioned in advance and concealed.
A bomb destroying a
rail trackjust before a trainarrives causes a train to derail. Apart from the damage to vehicles and people, a bomb exploding in a transportnetwork often also damages, and is sometimes mainly intended to damage that network. This applies for railways, bridges, runways, and ports, and to a lesser extent, depending on circumstances, to roads.
In the case of
suicide bombingthe bomb is often carried by the attacker on his or her body, or in a vehicle driven to the target.
Blue Peacocknuclear mines, which were also termed "bombs", were planned to be positioned during wartime and be constructed such that, if they were disturbed, they would explode within ten seconds.
The explosion of a bomb may be triggered by a
detonatoror a fuse. Detonators are triggered by clocks, remote controls like cell phones or some kind of sensor, such as pressure (altitude), radar, vibration or contact. Detonators vary in ways they work, they can be electrical, fire fuze or blast initiated detonators and others..
* [http://www.fas.org/man/dod-101/sys/dumb/bombs.htm FAS.org] Bombs for Beginners
* [http://www.makeitlouder.com/document_bombshockwaveestimation.html MakeItLouder.com] How a bomb functions and rating their power
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