An explosive (or explosive material) is a reactive substance that contains a great amount of potential energy that can produce an explosion if released suddenly, usually accompanied by the production of light, heat, sound, and pressure. An explosive charge is a measured quantity of explosive material. The material may either be composed solely of one ingredient or be a mixture containing at least two substances.
The potential energy stored in an explosive material may, for example, be:
Drilling and blasting is the controlled use of explosives and other methods, such as gas pressure blasting pyrotechnics, to break rock for excavation. It is practiced most often in mining, quarrying and civil engineering such as dam, tunnel or road construction. The result of rock blasting is often known as a rock cut.
Drilling and blasting currently utilizes many different varieties of explosives with different compositions and performance properties. Higher velocity explosives are used for relatively hard rock in order to shatter and break the rock, while low velocity explosives are used in soft rocks to generate more gas pressure and a greater heaving effect. For instance, an early 20th-century blasting manual compared the effects of black powder to that of a wedge, and dynamite to that of a hammer. The most commonly used explosives in mining today are ANFO based blends due to lower cost than dynamite.
Incendiary weapons, incendiary devices, incendiary munitions, or incendiary bombs are weapons designed to start fires. They may destroy structures or sensitive equipment using fire, and sometimes operate as anti-personnel weaponry. Incendiaries utilize materials such as napalm, thermite, magnesium powder, chlorine trifluoride, or white phosphorus. Though colloquially often called "bombs", they are not explosives but in fact operate to slow the process of chemical reactions and use ignition rather than detonation to start or maintain the reaction. Napalm, for example, is petroleum especially thickened with certain chemicals into a gel to slow, but not stop, combustion, releasing energy over a longer time than an explosive device. In the case of napalm, the gel adheres to surfaces and resists suppression.
An explosive belt (also called suicide belt, suicide vest or bomb vest) is an improvised explosive device, a belt or a vest packed with explosives and armed with a detonator, worn by suicide bombers. Explosive belts are usually packed with ball bearings, nails, screws, bolts, and other objects that serve as shrapnel to maximize the number of casualties in the explosion.
The Turnip Winter (German: Steckrübenwinter, pronounced [ˈʃtɛkʁyːbn̩ˌvɪntɐ]) of 1916 to 1917 was a period of profound civilian hardship in Germany during World War I, named for the resulting use of turnips as a famine food.
The Turnip Winter occurred during the winter of 1916–1917. Continually poor weather conditions led to a diminished harvest, most notably in cereal production. An ongoing blockade by the Allies of World War I had also reduced Germany's food imports. The food shortages were also attributed to a seizure of horses for the Imperial German Army, the conscription of a large part of the agricultural workforce, and a shortage of farming fertilizers caused by the diversion of nitrogen to the production of explosives. In response to the food shortage, the German government introduced food rationing through the then-new War Food Office. In the summer of 1917, the food allocated offered only 1,560 calories (6,500 kJ) daily diet and dropped to 1,000 calories per day in winter. The Imperial Health Office (renamed "Reich Health Office" in 1918) required 3,000 calories (12,600 kJ) for a healthy adult male, three times what was available in winter. German soldiers relied for their survival on the availability of turnips. Driven by starvation, children started breaking into barns and looting orchards in search of food. Such disregard for authority effectively doubled the youth crime rate in Germany. Historian G.J. Meyer noted that, according to a report from a prominent Berlin physician, "eighty thousand children had died of starvation in 1916". Worker strikes were also common during this time as food shortages often directly led to labor unrest.
A Hesco bastion,also known as a Hesco barrier, and formally Concertainer, is a gabion introduced in 1989 and primarily used for flood control and military fortifications. It is made of a collapsible wire mesh container and heavy-duty geotextile fabric liner and is used as a temporary to semi-permanent levee or blast wall against small-arms fire or explosives. It has been used in military applications in Iraq and Afghanistan.
The exploding-bridgewire detonator (EBW, also known as exploding wire detonator) is a type of detonator used to initiate the detonation reaction in explosive materials, similar to a blasting cap because it is fired using an electric current. EBWs use a different physical mechanism than blasting caps, using more electricity delivered much more rapidly. They explode with more precise timing after the electric current is applied by the process of exploding wire. The precise timing of exploding wire detonators compared with other types of detonators has led to their common use in nuclear weapons.
The slapper detonator is a more recent development along similar lines.
In thermodynamics, the Helmholtz free energy (or Helmholtz energy) is a thermodynamic potential that measures the useful work obtainable from a closed thermodynamic system at a constant temperature (isothermal). The change in the Helmholtz energy during a process is equal to the maximum amount of work that the system can perform in a thermodynamic process in which temperature is held constant. At constant temperature, the Helmholtz free energy is minimized at equilibrium.
In contrast, the Gibbs free energy or free enthalpy is most commonly used as a measure of thermodynamic potential (especially in chemistry) when it is convenient for applications that occur at constant pressure. For example, in explosives research Helmholtz free energy is often used, since explosive reactions by their nature induce pressure changes. It is also frequently used to define fundamental equations of state of pure substances.