為甚麼sloping edge能夠減少reflected waves?

2008-06-10 1:05 am
在我的Physics教科書中,有一句提到:「In order to reduce the unwanted reflected waves produced un a ripple tank, the tank is often designed to have a gentle sloping edge lined with absorbent material such as sponge.」

但是,為甚麼sloping edge能夠減少reflected waves?

回答 (2)

2008-06-10 7:09 am
✔ 最佳答案
For vertical edge:
Wave will be reflected back horizontally.

For sloping edge:
Wave will be reflected slightly upward.
So, horizontal reflectional wave is reduced.
2008-06-10 7:18 am
以下全為個人猜度,如有不對之處,敬希原諒。

I believe that you know pretty well that the velocity (or speed) of water waves decreases as the water depth decreases.
[Because the wavelength decreases under refraction.]

As a wave moves slower, the energy (KE, I believe) stored in the wave decreases.

Moreover, the energy (amplitude) of a wave decreases as it propagates. (Please do not ask me why, that is what my teacher told me... XP)

So, as the waves slow down in shallow water, the energy decreases. AND as they propagate, the energy also decreases.

I guess, may I emphasize, I GUESS, that the water waves travelling "across" the sloping egdes experience a sharp decrease in energy that the energy drops to zero (or almost zero), i.e. the waves "disappear".

I am not sure about it, yet does the above not sound reasonable? XD



Hope it helps.=]]

2008-06-09 23:19:48 補充:
看了上面的,有種「啊,原來如此!」的感覺。


請華麗的無視這邊的廢話吧。XD
參考: moi, not sure whether it is correct or not, though


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