Explosion

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Explode
)
The explosion of 4,685 tonnes of explosives.
The explosion of the Castle Bravo nuclear bomb.

An explosion is a rapid expansion in

low explosives through a slower combustion process known as deflagration
.

Causes

For an explosion to occur, there must be a rapid, forceful expansion of matter. There are numerous ways this can happen, both naturally and artificially, such as

bushfires in eucalyptus forests where the volatile oils in the tree tops suddenly combust.[1]

Astronomical

Among the largest known explosions in the universe are

explodes in its atmosphere, such as a planet. This occurs because the two objects are moving at very high speed relative to each other (a minimum of 11.2 kilometres per second (7.0 mi/s) for an Earth impacting body[3]). For example, the Tunguska event of 1908 is believed to have resulted from a meteor air burst.[4]

Black hole mergers, likely involving binary black hole systems, are capable of radiating many solar masses of energy into the universe in a fraction of a second, in the form of a gravitational wave. This is capable of transmitting ordinary energy and destructive forces to nearby objects, but in the vastness of space, nearby objects are rare.[5] The gravitational wave observed on 21 May 2019, known as GW190521, produced a merger signal of about 100 ms duration, during which time is it estimated to have radiated away nine solar masses in the form of gravitational energy.

Chemical

The most common artificial explosives are chemical explosives, usually involving a rapid and violent

Frederick Augustus Abel's development of nitrocellulose in 1865 and Alfred Nobel's invention of dynamite
in 1866. Chemical explosions (both intentional and accidental) are often initiated by an electric spark or flame in the presence of oxygen. Accidental explosions may occur in fuel tanks, rocket engines, etc.

Electrical and magnetic

A capacitor that has exploded

A high current electrical fault can create an "electrical explosion" by forming a high-energy electrical arc which rapidly vaporizes metal and insulation material. This arc flash hazard is a danger to people working on energized switchgear. Excessive magnetic pressure within an ultra-strong electromagnet can cause a magnetic explosion.

Mechanical and vapor

Strictly a physical process, as opposed to chemical or nuclear, e.g., the bursting of a sealed or partially sealed container under internal pressure is often referred to as an explosion. Examples include an overheated boiler or a simple tin can of beans tossed into a fire.

Boiling liquid expanding vapor explosions are one type of mechanical explosion that can occur when a vessel containing a pressurized liquid is ruptured, causing a rapid increase in volume as the liquid evaporates. Note that the contents of the container may cause a subsequent chemical explosion, the effects of which can be dramatically more serious, such as a propane
tank in the midst of a fire. In such a case, to the effects of the mechanical explosion when the tank fails are added the effects from the explosion resulting from the released (initially liquid and then almost instantaneously gaseous) propane in the presence of an ignition source. For this reason, emergency workers often differentiate between the two events.

Nuclear

In addition to stellar nuclear explosions, a nuclear weapon is a type of explosive weapon that derives its destructive force from nuclear fission or from a combination of fission and fusion. As a result, even a nuclear weapon with a small yield is significantly more powerful than the largest conventional explosives available, with a single weapon capable of completely destroying an entire city.

Properties

Force

A breaching charge exploding against a test door during training

Explosive force is released in a direction perpendicular to the surface of the explosive. If a grenade is in mid air during the explosion, the direction of the blast will be 360°. In contrast, in a shaped charge the explosive forces are focused to produce a greater local explosion; shaped charges are often used by military to breach doors or walls.

Velocity

The speed of the reaction is what distinguishes an explosive reaction from an ordinary combustion reaction. Unless the reaction occurs very rapidly, the thermally expanding gases will be moderately dissipated in the medium, with no large differential in pressure and no explosion. As a wood fire burns in a fireplace, for example, there certainly is the evolution of heat and the formation of gases, but neither is liberated rapidly enough to build up a sudden substantial pressure differential and then cause an explosion. This can be likened to the difference between the energy discharge of a

battery, which is slow, and that of a flash capacitor like that in a camera
flash, which releases its energy all at once.

Evolution of heat

The generation of heat in large quantities accompanies most explosive chemical reactions. The exceptions are called

Heat of Combustion
for a more thorough treatment of this topic.

When a chemical compound is formed from its constituents, heat may either be absorbed or released. The quantity of heat absorbed or given off during transformation is called the

exothermic
—that have a net liberation of heat and have a negative heat of formation—are of interest. 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 the "heat of explosion."

Initiation of 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.

A reaction must be capable of being initiated by the application of shock, heat, or a

catalyst
(in the case of some explosive chemical reactions) 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 needed.

Fragmentation

Fragmentation is the accumulation and projection of particles as the result of a high explosives detonation. Fragments could originate from: parts of a structure (such as

strata and/or various surface-level geologic features (such as loose rocks, soil, or sand
), the casing surrounding the explosive, and/or any other loose miscellaneous items not vaporized by the shock wave from the explosion. High velocity, low angle fragments can travel hundreds of metres with enough energy to initiate other surrounding high explosive items, injure or kill personnel, and/or damage vehicles or structures.

Notable examples

Chemical


Nuclear

Volcanic

Stellar

Airbursts/Impact events

Transport/Aviation

Other

Etymology

Classical Latin explōdō means "to hiss a bad actor off the stage", "to drive an actor off the stage by making noise", from ex- ("out") + plaudō ("to clap; to applaud"). The modern meaning developed later:[7]

  • Classical Latin: "to drive an actor off the stage by making noise" hence meaning "to drive out" or "to reject"

In English:

  • Around 1538: "drive out or off by clapping" (originally theatrical)
  • Around 1660: "drive out with violence and sudden noise"
  • Around 1790: "go off with a loud noise"
  • Around 1882: first use as "bursting with destructive force"

See also

References

  1. ^ Kissane, Karen (2009-05-22). "Fire power equalled 1500 atomic bombs". The Age. Melbourne. Archived from the original on 2009-05-27.
  2. ^ Van Der Sluys, M. V.; Lamers, H. J. G. L. M. (2003). "The dynamics of the nebula M1-67 around the run-away Wolf-Rayet star WR 124". Astronomy and Astrophysics. 398: 181–194.
    S2CID 6142859
    .
  3. ^ Koeberl, Christian; Sharpton, Virgil L. "Compiled by Christian Koeberl and Virgil L. Sharpton".
  4. ^ "115 Years Ago: The Tunguska Asteroid Impact Event - NASA". 2023-07-05. Retrieved 2023-11-07.
  5. ^ Siegel, Ethan (15 February 2020). "Ask Ethan: Could Gravitational Waves Ever Cause Damage On Earth? Starts With A Bang". Forbes. Retrieved 7 September 2020.
  6. PMID 15669854
    .
  7. ^ wikt:explode#Etymology