Wednesday, July 25, 2007

童玩一

今期 Acoustics Bulletin Vol 32 轉載了 "The Journal of the New Zealand Acoustical Society Vol 19" 中的一篇文章 "A Brief History of the Speed of Sound - L. Hannah (2006)"。

很可惜這文在網上沒得看。 文的前半我看得津津有味,後半太深了沒心理去理解。

為找出聲音之速度,十五世紀有科學家做過這樣的實驗:

The first explicit mention of sound velocity appears to be by Francis Bacon. He discussed the possibility of comparing the velocity of sound with that of light (which he knew at the time to be immeasurably high) by comparing the time taken for the sound of a church bell to travel one mile (1.6km) with that taken by simultaneous light signal (an interrupted light taper) over the same distance, by using his own pulse as the timing mechanism......


讀到這裡我想起在兒時(大概是中一二吧)玩過的類似遊戲,計算行雷的位置。 玩法是以閃電的出現為基準,看到閃電後開始計時直至聽到雷聲為止,由時間的差距計算出地域的距離,用這距離作半徑在地圖上打圈,偉大的結論便是打雷的地方就是在圓周上發生了。 遊戲的構思便是這樣,但我總是算不來。

地圖的另一個玩法是坐標颱風的位置。 在沒有上網的年代,這些都是很好玩的。

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