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急:Heat and sound

Heat 求教 : 有高手可以幫破解嗎

1.A furnace wall is constructed of two layers off different materials having thermal conductivities

0.38 and 1.629W/mK respectively. the inner surface is maintained at 600(攝氏度) and the outer surface at 460(攝氏度). Calculate (a) the heat flux per unit area, (b) temperature at the interface when the layer are 10 cm and 20cm thick respectively. Neglect surface resistances.

2.

A)Find the absolute sound pressure of a sound source with sound pressure

level of 100dB. given that the reference, p0 is 20uPa.

B)A sound wave is moving at 320 m/s, what is its frequency if the wave length is 1.6m?

C) A laboratory has six identical air-conditioners. When two of them are turned on, the sound pressure level, SPL recorded is 65dB, Determine the sound pressure level if all the air-conditioners are turned on.

1 個解答

評分
  • joyce
    Lv 5
    8 年前
    最愛解答

    B) velocity =frequency X wavelength

    320 = 1.6f

    f = 200Hz

    資料來源: 才疏學淺的小人.....
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