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謝謝幫我看看這題 這是聲波單元的題目， http://a.imageshack.us/img843/2277/zo8a.jpg 圖片可放大喔^^
最佳解答:
Speed of sound in a gas = square-root[bulk modulus/density] hence, speed of sound in tube A, Va = square-root[16Bo/po] = 4k where k = square-root(Bo/po) Similarly, speed of sound in tube B, Vb = square-root[4Bo/po] = 2k speed of sound in tube C, Vc = square-root[Bo/po] = k Now, total length of tube A, La = (L + L + 2L + L + L) = 6L Total length of tube B, Lb = (L + L + L) = 3L Total length of tube C, Lc = 2L Because time t = length of tube/speed of sound hence, time for sound to pass through tube A, ta = 6L/Va = 6L/4k = 3L/2k Ttime for sound to pass through tube B, tb = 3L/Vb = 3L/2k Time for sound to pass through tube C, tc = 2L/Vc = 2L/k Therefore, ta = tb < tc
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聲波傳播 ，我不知道這題該怎麼看呢?還是怎麼算?發問:
謝謝幫我看看這題 這是聲波單元的題目， http://a.imageshack.us/img843/2277/zo8a.jpg 圖片可放大喔^^
最佳解答:
Speed of sound in a gas = square-root[bulk modulus/density] hence, speed of sound in tube A, Va = square-root[16Bo/po] = 4k where k = square-root(Bo/po) Similarly, speed of sound in tube B, Vb = square-root[4Bo/po] = 2k speed of sound in tube C, Vc = square-root[Bo/po] = k Now, total length of tube A, La = (L + L + 2L + L + L) = 6L Total length of tube B, Lb = (L + L + L) = 3L Total length of tube C, Lc = 2L Because time t = length of tube/speed of sound hence, time for sound to pass through tube A, ta = 6L/Va = 6L/4k = 3L/2k Ttime for sound to pass through tube B, tb = 3L/Vb = 3L/2k Time for sound to pass through tube C, tc = 2L/Vc = 2L/k Therefore, ta = tb < tc
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