1问题的提出运动的合成与分解是中学物理教学的难点之一,特别是由绳子牵连的物体的速度分解,几乎出现于所有的同步教辅材料中,其典型示例为:如图1所示,在河岸上用定滑轮拉绳子使小船靠岸,拉动绳子的速度v0大小恒定,当拉着船头的绳子与水面夹角为θ时,求小船沿水面的行驶速度v。 1 Problem formulation The synthesis and decomposition of motion is one of the difficulties in the teaching of physics in middle schools, especially the decomposition of the velocity of the objects implicated by the rope, which occurs almost in all synchronous teaching and auxiliary materials. Typical examples are as follows: On the river bank, pull the rope with a fixed pulley to make the boat beach. The speed v0 of pulling the rope is constant. When the angle between the rope pulling the bow and the water surface is θ, seek the speed of the boat along the water surface v.