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In physics, the ballistic trajectory of a projectile is the path that a thrown or launched projectile or missile will take under the action of gravity, neglecting all other forces, such as friction from aerodynamic drag, without propulsion. The United States Department of Defense and NATO define a ballistic trajectory as a trajectory traced after the propulsive force is terminated and the body is acted upon only by gravity and aerodynamic drag. The following applies for ranges which are small compared to the size of the Earth. For longer ranges see sub-orbital spaceflight. ==Notation== In the equations on this page, the following variables will be used: * g: the gravitational acceleration—usually taken to be 9.81 m/s2 near the Earth's surface * θ: the angle at which the projectile is launched * v: the speed at which the projectile is launched * y0: the initial height of the projectile * d: the total horizontal distance traveled by the projectile Ballistics (gr. βάλλειν ('ba'llein'), "to throw") is the science of mechanics that deals with the flight, behavior, and effects of projectiles, especially bullets, gravity bombs, rockets, or the like; the science or art of designing and accelerating projectiles so as to achieve a desired performance. A ballistic body is a body which is free to move, behave, and be modified in appearance, contour, or texture by ambient conditions, substances, or forces, as by the pressure of gases in a gun, by rifling in a barrel, by gravity, by temperature, or by air particles. A ballistic missile is a missile only guided during the relatively brief initial powered phase of flight, whose course is subsequently governed by the laws of classical mechanics. These formulae ignore aerodynamic drag and also assume that the landing area is at uniform height 0. 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「trajectory of a projectile」の詳細全文を読む スポンサード リンク
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