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A trajectory or flight path is the path that a moving object follows through space as a function of time.〔The Principles of Physics by Rohit Metha, Chapter 11 Page 378 Para 3〕 The object might be a projectile or a satellite. For example. It can be an orbit—the path of a planet, an asteroid or a comet as it travels around a central mass. A trajectory can be described mathematically either by the geometry of the path, or as the position of the object over time. In control theory a trajectory is a time-ordered set of states of a dynamical system (see e.g. Poincaré map). In discrete mathematics, a trajectory is a sequence of values calculated by the iterated application of a mapping to an element of its source. == Physics of trajectories == A familiar example of a trajectory is the path of a projectile, such as a thrown ball or rock. In a greatly simplified model the object moves only under the influence of a uniform gravitational force field. This can be a good approximation for a rock that is thrown for short distances, for example, at the surface of the drag and aerodynamics). This is the focus of the discipline of ballistics. One of the remarkable achievements of Newtonian mechanics was the derivation of the laws of Kepler. In the gravitational field of a point mass or a spherically-symmetrical extended mass (such as the Sun), the trajectory of a moving object is a conic section, usually an ellipse or a hyperbola.(t)} = -\nabla V(\vec(t)) with On the right-hand side, the force is given in terms of , the gradient of the potential, taken at positions along the trajectory. This is the mathematical form of Newton's second law of motion: force equals mass times acceleration, for such situations. 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」の詳細全文を読む スポンサード リンク
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