Bombs

A bomb is an explosive device that, although not containing more energy than ordinary fuel, except in the case of a nuclear weapon, generates and releases its energy very rapidly, as an explosion, 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 word 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, although the people using the devices may or may not sometimes refer to them as bombs. 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 when in missiles, or land mines.

They have been used for centuries in warfare and are a central part of a terrorist's arsenal. They fall into three distinct categories: conventional if filled with chemical explosives, dispersive if filled with submunitions, chemicals or other disruptive agents which are spread on or shortly before impact, or nuclear if relying on nuclear fission or nuclear fusion for their effect.

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, 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 (IEDs).

The most powerful bomb in existence is the hydrogen bomb, a nuclear weapon. The most powerful bombs ever used in combat were the two nuclear bombs 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 Blast).

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.

Another type of bomb is called an EMP (Electro-Magnetic Pulse) and its primary function is to terminate all working electrical equipment in the vicinity. Its power can range from one machine to an entire state.


Delivery

The usual method of delivering military bombs to their target is by bombing, i.e. dropping them from a bomber airplane. Modern bombs, precision-guided munitions, may be guided after they leave an airplane by remote control, by autonomous guidance 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", which was an 11kg 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 the case that the aircraft releases the bomb at low altitude.

A hand grenade is 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 rifle using the M203 or the GP-30 or by attaching a rocket to the explosive grenade as in a rocket propelled grenade (RPG).

A bomb may also be positioned in advance and concealed, for example in a garbage container, car or truck as a car bomb, or by the roadside in a roadside bomb, in a building as a booby trap, or in lugguage and in a vehicle.

A bomb destroying a rail track just before a train arrives causes a train to derail. Apart from the damage to vehicles and people, a bomb exploding in a transport network 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 bombing the bomb is often carried by the attacker on his or her body, or a in a vehicle driven to the target.

The Blue Peacock nuclear 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.
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Detonation

The explosion of the bomb has to be triggered by a detonator or 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.
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Bombing

Bombing may be directed at military targets; such as ships, logistic and transportation centres, warehouses or weapons industries such as armament factories. They may be detonated also at civilian targets, such as office buildings, commercial areas or whole cities. Bombing of particular targets such as ships, railroad trains or military vehicles such as tanks is called tactical bombing; bombing of areas such as military bases or infrastructure, such as bridges, industrial centres, transport facilities) is called strategic bombing. Strategic bombing of civilian targets is controversial and considered a war crime by most and a defining characteristic of terrorism by others, and may be considered terror bombing. Area or carpet bombing of cities using incendiary bombs may result in a firestorm and extensive casualties especially when the city is fire-prone, largely constructed of timber buildings or used to store flammable materials, and it is windy.