Bomb

A bomb is an explosive weapon that uses the exothermic reaction of an explosive material to provide an extremely sudden and violent release of energy. Detonations inflict damage principally through ground- and atmosphere-transmitted mechanical stress, the impact and penetration of pressure-driven projectiles, pressure damage, and explosion-generated effects. Bombs have been in use since the 11th century in Song Dynasty China.

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 sometimes refer to them as a "bomb". The military use of the term "bomb", or more specifically aerial bomb action, typically refers to airdropped, unpowered explosive weapons most commonly used by air forces and naval aviation. Other military explosive weapons not classified as "bombs" include grenades, shells, depth charges (used in water), warheads when in missiles, or land mines. In unconventional warfare, "bomb" can refer to a range of offensive weaponry. For instance, in recent conflicts, "bombs" known as improvised explosive devices (IEDS) have been employed by insurgent fighters to great effectiveness.

North Korea

Coordinates: 40°00′N 127°00′E / 40.000°N 127.000°E / 40.000; 127.000

North Korea ( listen), officially the Democratic People's Republic of Korea (DPRK; Chosŏn'gŭl: 조선민주주의인민공화국; hancha: 朝鮮民主主義人民共和國; MR: Chosŏn Minjujuŭi Inmin Konghwaguk), is a country in East Asia, in the northern part of the Korean Peninsula. The name Korea is derived from the Kingdom of Goguryeo, also spelled as Koryŏ. The capital and largest city is Pyongyang. North Korea shares a land border with China to the north and northwest, along the Amnok (Yalu) and Tumen rivers, and a small section of the Tumen River also forms a border with Russia to the northeast. The Korean Demilitarized Zone marks the boundary between North Korea and South Korea.

Korea was annexed by the Empire of Japan in 1910. After the Japanese surrender at the end of World War II in 1945, Korea was divided into two zones by the United States and the Soviet Union, with the north occupied by the Soviets and the south by the Americans. Negotiations on reunification failed, and in 1948 two separate governments were formed: the Democratic People's Republic of Korea in the north, and the Republic of Korea in the south. An invasion initiated by North Korea led to the Korean War (1950–53). Although the Korean Armistice Agreement brought about a ceasefire, no official peace treaty was ever signed. Both states were accepted into the United Nations in 1991.

Pacific Ocean

The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south and is bounded by Asia and Australia in the west and the Americas in the east.

At 165.25 million square kilometers (63.8 million square miles) in area, this largest division of the World Ocean—and, in turn, the hydrosphere—covers about 46% of the Earth's water surface and about one-third of its total surface area, making it larger than all of the Earth's land area combined.

The equator subdivides it into the North Pacific Ocean and South Pacific Ocean, with two exceptions: the Galápagos and Gilbert Islands, while straddling the equator, are deemed wholly within the South Pacific. The Mariana Trench in the western North Pacific is the deepest point in the world, reaching a depth of 10,911 metres (35,797 ft).

The eastern Pacific Ocean was first sighted by Europeans in the early 16th century when Spanish explorer Vasco Núñez de Balboa crossed the Isthmus of Panama in 1513 and discovered the great "southern sea" which he named Mar del Sur. The ocean's current name was coined by Portuguese explorer Ferdinand Magellan during the Spanish circumnavigation of the world in 1521, as he encountered favourable winds on reaching the ocean. He called it Mar Pacifico, which in both Portuguese and Spanish means "peaceful sea".

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Thermonuclear weapon

A thermonuclear weapon is a nuclear weapon that uses the energy from a primary nuclear fission reaction to compress and ignite a secondary nuclear fusion reaction. The result is greatly increased explosive power when compared to single-stage fission weapons. It is colloquially referred to as a hydrogen bomb or H-bomb because it employs fusion of isotopes of hydrogen. The fission stage in such weapons is required to cause the fusion that occurs in thermonuclear weapons.

The first full scale thermonuclear test was done by the United States in 1952; the concept has since been employed by most of the world's nuclear powers in the design of their weapons. The modern design of all thermonuclear weapons in the United States is known as the Teller–Ulam configuration for its two chief contributors, Edward Teller and Stanislaw Ulam, who developed it in 1951 for the United States, with certain concepts developed with the contribution of John von Neumann. Similar devices were developed by the United Kingdom, China, and France.