题目如图1所示,一列横渡向右传播,试判断质点P、Q的振动方向. 方法1:波的成因法波的形成和传播中有两句话,前面的质点带动后面的质点振动,后面的质点重复前面质点的振动.据此,在紧靠P、Q两点且靠近波源的方向上取两点P’、Q’(图2),由图中看出P’在P点下方,由于P点将紧随P’运动,所以P将向下振动;同理,靠近波源的Q’在Q的上方,所以Q将向上振动. The problem is shown in Fig. 1. A column is crossed to the right and the direction of vibration of the particles P and Q is judged. Method 1: The formation and propagation of the wave of the wave There are two sentences in the formation and propagation of the wave. The preceding particle drives the vibration of the back particle. The following particle repeats the vibration of the previous particle. Based on this, two points P’, Q’ are taken in the direction close to P and Q and close to the wave source (Fig. 2). From the figure, P’ is below P point. Since P will move immediately following P’, P will vibrate downwards. Similarly, Q’ near the source will be above Q, so Q will vibrate upwards.