agd: Submarine

Evidence: 100 • authority: 72

A submarine (often shortened to sub) is a watercraft capable of independent operation underwater. (It differs from a submersible, which has more limited underwater capability.) The term "submarine" is also sometimes used historically or informally to refer to remotely operated vehicles and robots, or to medium-sized or smaller vessels (such as the midget submarine and the wet sub). Submarines are referred to as boats rather than ships regardless of their size. Although experimental submarines had been built earlier, submarine design took off during the 19th century, and submarines were adopted by several navies. They were first used widely during World War I (1914–1918), and are now used in…

Evidence: 48 • authority: 72

Evidence: 47 • authority: 92

Evidence: 45 • authority: 72

Evidence: 38 • authority: 72

Nuclear weapons design means the physical, chemical, and engineering arrangements that cause the physics package of a nuclear weapon to detonate. There are three existing basic design types: Pure fission weapons are the simplest, least technically demanding, were the first nuclear weapons built, and so far the only type ever used in warfare, by the United States on Japan in World War II. Pure fission weapons have been the first type to be built by new nuclear powers, as a step toward building more advanced weapons. Boosted fission weapons are fission weapons that use nuclear fusion reactions to generate high-energy neutrons that accelerate the fission chain reaction and increase its efficie…

Evidence: 38 • authority: 72

Evidence: 38 • authority: 72

Evidence: 31 • authority: 72

The Second Industrial Revolution, also known as the Technological Revolution, was a phase of rapid scientific discovery, standardization, mass production and industrialization from the late 19th century into the early 20th century. The First Industrial Revolution, which ended in the middle of the 19th century, was punctuated by a slowdown in important inventions before the Second Industrial Revolution started in 1870. Though a number of its events can be traced to earlier innovations in manufacturing, such as the establishment of a machine tool industry, the development of methods for manufacturing interchangeable parts, as well as the invention of the Bessemer process and open hearth furna…

Evidence: 30 • authority: 72

Evidence: 30 • authority: 72

The Pakistan Armed Forces (Urdu: پاکستان مسلح افواج; pronounced [ˈpɑːkˌɪstaːn mʊˈsəlˌle(ɦ) əfˈwɑːd͡ʒ]) are the military forces of Pakistan. It is the world's seventh-largest military measured by active military personnel and consists of three uniformed services—the Army, Navy, and the Air Force, which are backed by several paramilitary forces such as the National Guard and the Civil Armed Forces. As of the 2025 reforms, the highest-ranking military officer is the Chief of Defence Forces (CDF), who also serves concurrently as Chief of Army Staff (COAS), holding principal command authority over all three branches and overseeing war strategy, operations, joint force development, and resource a…

Evidence: 30 • authority: 72

Evidence: 22 • authority: 72

A steam engine is a heat engine that performs mechanical work using steam as its working fluid. The steam engine uses the force produced by steam pressure to push a piston back and forth inside a cylinder. This pushing force can be transformed by a connecting rod and crank into rotational force for work. The term "steam engine" is normally applied to reciprocating engines, although some authorities have also referred to the steam turbine and devices such as Hero's aeolipile as "steam engines". The essential feature of steam engines is that they are external combustion engines, where the working fluid is separated from the combustion products. The ideal thermodynamic cycle used to analyze th…