An explosive 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, which may either be composed solely of one ingredient or be a mixture containing at least two substances.
A brake is a mechanical device that inhibits motion by absorbing energy from a moving system. It is used for slowing or stopping a moving vehicle, wheel, axle, or to prevent its motion, most often accomplished by means of friction.
In modern archery, a compound bow is a bow that uses a levering system, usually of cables and pulleys, to bend the limbs. The compound bow was first developed in 1966 by Holless Wilbur Allen in North Kansas City, Missouri, and a US patent was granted in 1969. Compound bows are widely used in target practice and hunting.
A bearing is a machine element that constrains relative motion to only the desired motion and reduces friction between moving parts. The design of the bearing may, for example, provide for free linear movement of the moving part or for free rotation around a fixed axis; or, it may prevent a motion by controlling the vectors of normal forces that bear on the moving parts. Most bearings facilitate the desired motion by minimizing friction. Bearings are classified broadly according to the type of operation, the motions allowed, or the directions of the loads (forces) applied to the parts.
Nitrogen triiodide is an inorganic compound with the formula NI3. It is an extremely sensitive contact explosive: small quantities explode with a loud, sharp snap when touched even lightly, releasing a purple cloud of iodine vapor; it can even be detonated by alpha radiation. NI3 has a complex structural chemistry that is difficult to study because of the instability of the derivatives. Although nitrogen is more electronegative than iodine, the compound was so named due to its analogy to the compound nitrogen trichloride.
A blister is a small pocket of body fluid within the upper layers of the skin, usually caused by forceful rubbing (friction), burning, freezing, chemical exposure or infection. Most blisters are filled with a clear fluid, either serum or plasma. However, blisters can be filled with blood or with pus.
Tribology is the science and engineering of understanding friction, lubrication and wear phenomena for interacting surfaces in relative motion. It is highly interdisciplinary, drawing on many academic fields, including physics, chemistry, materials science, mathematics, biology and engineering. The fundamental objects of study in tribology are tribosystems, which are physical systems of contacting surfaces. Subfields of tribology include biotribology, nanotribology and space tribology. It is also related to other areas such as the coupling of corrosion and tribology in tribocorrosion and the contact mechanics of how surfaces in contact deform. Approximately 20% of the total energy expenditure of the world is due to the impact of friction and wear in the transportation, manufacturing, power generation, and residential sectors.
Flash powder is a pyrotechnic composition, a mixture of oxidizer and metallic fuel, which burns quickly (deflagrates) and produces a loud noise regardless of confinement. It is widely used in theatrical pyrotechnics and fireworks and was once used for flashes in photography.
The safety testing of explosives involves the determination of various properties of the different energetic materials that are used in commercial, mining, and military applications. It is highly desirable to measure the conditions under which explosives can be set off for several reasons, including: safety in handling, safety in storage, and safety in use.
Syahi is the tuning paste applied to the head of many South Asian percussion instruments like the dholki, jori, tabla, madal, mridangam, khol and pakhavaj.
Shock sensitivity is a comparative measure of the sensitivity to sudden compression of an explosive chemical compound. Determination of the shock sensitivity of a material intended for practical use is one important aspect of safety testing of explosives. A variety of tests and indices are in use, of which one of the more common is the Rotter Impact Test with results expressed as FoI At least four other impact tests are in common use, while various "gap tests" are used to measure sensitivity to blast shock.
Hexamethylene triperoxide diamine (HMTD) is a high explosive organic compound. HMTD is an organic peroxide, a heterocyclic compound with a cage-like structure. It is a primary explosive. It has been considered as an initiating explosive for blasting caps in the early part of 20th century, mostly because of its high initiating power and its inexpensive production. As such, it was quickly taken up as a primary explosive in mining applications. However, it has since been superseded by more (chemically) stable compounds such as dextrinated lead azide and DDNP. HMTD is widely used in amateur-made blasting caps.
A contact explosive is a chemical substance that explodes violently when it is exposed to a relatively small amount of energy. Though different contact explosives have varying amounts of energy sensitivity, they are all much more sensitive relative to other kinds of explosives. Contact explosives are a part of a group of explosives called primary explosives, which are also very sensitive to stimuli but not to the degree of contact explosives. The extreme sensitivity of contact explosives is due to either chemical composition, bond type, or structure.
A pyrotechnic composition is a substance or mixture of substances designed to produce an effect by heat, light, sound, gas/smoke or a combination of these, as a result of non-detonative self-sustaining exothermic chemical reactions. Pyrotechnic substances do not rely on oxygen from external sources to sustain the reaction.
Ammunition is the material fired, scattered, dropped, or detonated from any weapon or weapon system. Ammunition is both expendable weapons and the component parts of other weapons that create the effect on a target.
Tetrazene is an explosive material used for sensitization of priming compositions. It is a derivative of the compound with the IUPAC name tetrazene.
Acne mechanica is an acneiform eruption that has been observed after repetitive physical trauma to the skin such as rubbing, occurring from clothing or sports equipment. In addition to those mechanisms, the skin not getting enough exposure to air also contributes to the formation of acne mechanica. It is often mistaken as a rash that forms on sweaty skin that is constantly being rubbed, but in reality, it is a breakout of acne mechanica. The term "acne" itself describes the occurrence in which hair follicles in the skin get clogged by oil, dead skin cells, dirt and bacteria, or cosmetic products and create a pimple. Pimples can vary in type, size, and shape, but the sole basis of them occurring is the same - the oil gland in the pore becomes clogged and sometimes infected, which creates pus in order to fight the infection and subsequently causes the development of swollen, red lesions on the skin.
In explosives engineering, sensitivity refers to the degree to which an explosive can be initiated by impact, heat, or friction. Current in-use standard methods of mechanical senstivity determination differ by the sample preparation, sample arrangement, instrument type, go/not go criteria, and the statistical analysis of results.
Bromine azide is an explosive inorganic compound with the formula BrN3. It has been described as a crystal or a red liquid at room temperature. It is extremely sensitive to small variations in temperature and pressure, with explosions occurring at Δp ≥ 0.05 Torr and also upon crystallization, thus extreme caution must be observed when working with this chemical.
Azidotetrazolate (CN7−) is an anion which forms a highly explosive series of salts. The ion is made by removing a proton from 5-azido-1H-tetrazole. The molecular structure contains a five-membered ring with four nitrogen atoms, and an azido side chain connected to the carbon atom. Several salts exist, but they are unstable and spontaneously explode. Rubidium azidotetrazolate was so unstable that it explodes while crystallizing. The potassium and caesium salt also spontaneously explode when dry.
