采用两个极坐标系来表示动点的位置,经简单运算得出平面曲线运动中动点的速度和加速度的统一表达式。对动点的运动条件给予不同的限制,推证了各种运动情况下动点的速度和加速度的公式及有关定理。 Two polar coordinate systems are used to represent the position of the moving point, and a simple expression of the unified expression of the velocity and acceleration of the moving point in the planar curved motion is obtained. Different conditions are given to the moving conditions of moving points, and the formulas and related theorems of moving speed and acceleration of moving points are deduced.