理想的抛物运动，形式上是由两个彼此独立的分步的合成，一个是水平方向的匀速直线运动；另一个是竖直方向上的上抛或下抛运动（特殊情况下为自由落体运动）。实质是在大小和方向都不变的恒力（重力）作用下，初速度与恒力方向不在同一直线上而是成某一夹角的曲线运动。研究这 The ideal parabolic motion is formally composed of two independent step-by-step syntheses, one is a horizontal uniform linear motion; the other is a vertical upward or downward motion (in special cases, free-fall motion ). The essence is that under the constant force (gravity) whose size and direction are constant, the initial velocity and the constant force direction are not in the same straight line, but a curved motion with an included angle. Study this