rdfvjur的部落格

標題:

Sound Characteristics and Sound Intensity

發問:

1) When driven at a frequency of 420Hz, a strethced string has four equal loops in a standing wave. What driving frequency will set up a wave with two equal segments?2) The intensity level of a sound is 90 dB at a certain distance from its source. How much energy falls on an eardrum with a diameter of 1cm in 5... 顯示更多 1) When driven at a frequency of 420Hz, a strethced string has four equal loops in a standing wave. What driving frequency will set up a wave with two equal segments? 2) The intensity level of a sound is 90 dB at a certain distance from its source. How much energy falls on an eardrum with a diameter of 1cm in 5 second?

• 亞太門市 態度有夠差 超火 台北市信義區忠孝東路5段437號
• 機車強制險+駕駛人傷害險+第三人責任險
• 蔡依林所買的汽車
• XYZ題目
• 統一超商 電信
• 區議員議席數目
• 今年統測成績入學門檻
• 基隆撘車到台中市南屯區南屯路,該怎麼坐
• 可以從別校直接學期中轉學到振聲嗎-
• 二手琴行賣的YAMAHA鋼琴, 有廿多年琴齡, 點解可以整到好似新一樣呢-

 

此文章來自奇摩知識+如有不便請留言告知

最佳解答:

1) Comparing the wavelengths between the cases of 4 equal loops and 2 equal loops, we can see that the wavelength in the case of 2 equal loops is double of that of the case of 4 equal loops. So suppose that the string tension remains unchanged (implying that the wave velocity on the string remains unchanged), the driving frequency in the case of 2 equal loops should be half of that of the case of 4 equal loops, i.e. 420/2 = 210 Hz. 2) Applying the sound intensity of threshold of hearing = 10-12 W/m2, we have, at a level of 90 dB, the sound intensity is give by: 10 log (I/10-12) = 90 I = 10-3 W/m2 So the power transmitted on an eardrum with a diameter of 1cm is given by: P = 10-3 × π(0.01/2)2 = 7.85 × 10-8 W Finally, amount of energy falling on the eardrum in 5 secods = 7.85 × 10-8 × 5 = 3.93 × 10-7 J

其他解答:D1B39E804036C6BD