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A projectile is any object thrown into space (empty or not) by the exertion of a force. 〔http://www.merriam-webster.com/dictionary/projectile〕 Although any object in motion through space (for example a thrown baseball) may be called a projectile, the term more commonly refers to a ranged weapon. Mathematical equations of motion are used to analyze projectile trajectory. ==Motive force== Arrows, darts, spears, and similar weapons are fired using pure mechanical force applied by another object; apart from throwing without tools, mechanisms include the catapult, slingshot, and bow. Other weapons use the compression or expansion of gases as their motive force. Blowguns and pneumatic rifles use compressed gases, while most other guns and cannons utilize expanding gases liberated by sudden chemical reactions. Light-gas guns use a combination of these mechanisms. Railguns utilize electromagnetic fields to provide a constant acceleration along the entire length of the device, greatly increasing the muzzle velocity. Some projectiles provide propulsion during flight by means of a rocket engine or jet engine. In military terminology, a rocket is unguided, while a missile is guided. Note the two meanings of "rocket" (weapon and engine): an ICBM is a missile with rocket engines. Ballistics analyze the projectile trajectory, the forces acting upon the projectile, and the impact that a projectile has on a target. An explosion, whether or not by a weapon, causes the debris to act as multiple high velocity projectiles. An explosive weapon, or device may also be designed to produce many high velocity projectiles by the break-up of its casing, these are correctly termed fragments. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「projectile」の詳細全文を読む スポンサード リンク
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