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机械波概念的抽象性,传播方向的双向性,波的图像的周期性及振动图像与波的图像之间的相互的干扰,造成了波动问题的复杂性,在解题时,如充分利用图像可增强直观性,加深对波的理解,从而迅速准确的求解.下面举例说明波的图像在解题中应用的几种类型.一、根据波的传播方向确定各质点的振动方向已知t时刻波的图象和波的传播方向时,先将波沿着传播方向向前平移△x,得到t+△t时刻的波的图象.根据波传播过程中每个质点都在自己的平衡位置附近振动,物质本身并不发生位移的特点,画出某质点t到t+Δt时刻的位移,即为该质点的振动方向.反之,也可根据t时刻某质点的振动方向画出下一时刻的波形,从而判断出波的传播方向.例1一列沿x正方向传播的横波,t时刻的波形如图1所示,判断此时刻波中4、B、C、D四个质点的振动方向.分析:将波向右平移画出下一时刻的波形,如图1中虚线所
The abstraction of the concept of mechanical wave, the bidirectional nature of the direction of propagation, the periodicity of the image of the wave and the mutual interference of the image of the vibration and the wave cause the complexity of the wave problem. When the problem is solved, such as making full use of the image Enhance intuition, and deepen the understanding of the wave, so as to quickly and accurately solve.The following examples illustrate the wave image in the problem-solving applications of several types.First, according to the direction of wave propagation to determine the vibration direction of each particle known t moment wave Image and wave propagation direction, the first wave along the propagation direction of the forward shift △ x, get t + △ t moment of the wave image.According to each particle in the wave propagation process in the vicinity of their own equilibrium position vibration , The displacement of the material itself does not occur, draw a point of t to t + Δt moment of displacement, that is, the vibration of the particle direction.On the other hand, can also be based on the vibration point t at a certain point of time to draw the waveform of the next moment , To determine the direction of wave propagation.Example 1 A series of transverse waves propagating in the positive x direction, the waveform at time t as shown in Figure 1, to determine the vibration direction of the four particles at 4, B, C, D at this moment. : Shift the wave to the right to draw the next wave Shaped, as shown in Figure 1 dotted line