User:Wener-6022/平抛运动
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Projectile motion is a form of motion experienced by an object or particle (a projectile) that is projected near the Earth's surface and moves along a curved path under the action of gravity only (in particular, the effects of air resistance are assumed to be negligible). This curved path was shown by Galileo to be a parabola, but may also be a line in the special case when it is thrown directly upwards. The study of such motions is called ballistics, and such a trajectory is a ballistic trajectory. The only force of significance that acts on the object is gravity, which acts downward, thus imparting to the object a downward acceleration. Because of the object's inertia, no external horizontal force is needed to maintain the horizontal velocity component of the object. Taking other forces into account, such as friction from aerodynamic drag or internal propulsion such as in a rocket, requires additional analysis. A ballistic missile is a missile only guided during the relatively brief initial powered phase of flight, and whose subsequent course is governed by the laws of classical mechanics.||平抛运动是物体或粒子在地球表面被投射在仅受重力作用的情况下沿曲线运动的运动形式。(通常的,空气阻力在此忽略不计),这条曲线被伽利略展示被叫做抛物线,但在特殊情况下向上抛掷会是一条直线。对这种运动的研究称之为弹道学。而这样的轨迹就称之为弹道轨迹,唯一作用在物体上的力就是作用力向下重力,从而赋予物体一个向下的加速度。因为物体的惯性,无需外部作用力保持水平。考虑其他力时需要其他分析比如火箭与空气的摩擦阻力或内部推进力。弹道导弹只在相对简短的初始动力飞行阶段进行引导,其后继路线受古典力学的支配。
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Ballistics (gr. βάλλειν ('ba'llein'), "to throw") is the science of mechanics that deals with the flight, behavior, and effects of projectiles, especially bullets, unguided bombs, rockets, or the like; the science or art of designing and projectiles so as to achieve a desired performance.||弹道学(希腊文:βάλλειν,('ba'llein'), "to throw")是研究抛掷物(如比如子弹、非制导武器、火箭)的飞行轨迹、表现和影响的力学,设计和加速使性能升级的科学或艺术。
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The elementary equations of ballistics neglect nearly every factor except for initial velocity and an assumed constant gravitational acceleration. ||弹道学的基本方程忽略了除了初始速度和假定恒定的重力加速度以外的的所有因素。Practical solutions of a ballistics problem often require considerations of air resistance, cross winds, , varying acceleration due to gravity, and in such problems as launching a rocket from one point on the Earth to another, the rotation of the Earth.|弹道问题的现实解决方案通常需要考虑空气阻力,逆风,目标运动,由重力而变化的加速度,以及从地球上一个点向另一个点发射火箭的问题(需考虑地球自转)| Detailed mathematical solutions of practical problems typically do not have closed-form solutions, and therefore require numerical methods to address.|实际问题的详细数学解决方案通常没有解析解,需要用数值分析来解决。