Random physics question
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Was lying in bed last night with the fan and the radio on, when a physics problem came into my mind. In a wind tunnel you have source of sound, speaker, and a few listeners positions upwind and downwind of the speaker. Assuming the speaker is loud enough over the volume of the wind/fan, would the sound have a harder time of reaching the upwind reciever compared to the downwind reciever? In other words, If you got the wind speed up or even past the speed of sound would the reciever upwind hear nothing, and the downwind reciever here everything? :confused::confused::confused: Greba, My lack of content on my home page should be entertaining.
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Was lying in bed last night with the fan and the radio on, when a physics problem came into my mind. In a wind tunnel you have source of sound, speaker, and a few listeners positions upwind and downwind of the speaker. Assuming the speaker is loud enough over the volume of the wind/fan, would the sound have a harder time of reaching the upwind reciever compared to the downwind reciever? In other words, If you got the wind speed up or even past the speed of sound would the reciever upwind hear nothing, and the downwind reciever here everything? :confused::confused::confused: Greba, My lack of content on my home page should be entertaining.
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Was lying in bed last night with the fan and the radio on, when a physics problem came into my mind. In a wind tunnel you have source of sound, speaker, and a few listeners positions upwind and downwind of the speaker. Assuming the speaker is loud enough over the volume of the wind/fan, would the sound have a harder time of reaching the upwind reciever compared to the downwind reciever? In other words, If you got the wind speed up or even past the speed of sound would the reciever upwind hear nothing, and the downwind reciever here everything? :confused::confused::confused: Greba, My lack of content on my home page should be entertaining.
greba wrote: would the sound have a harder time of reaching the upwind reciever Yes, because sound is actually a pressure wave moving through the air. It requires one air molecule to bang into the next, transferring kinetic energy to make it bang into the next... and so on. If those molecules are all moving away from you at the same time all that is happening, it will take longer for the wave to reach you, which also means the sound has to have more energy (ie, be louder at the source) to reach you. Think of an analogous situation - you're in a chair with rollers and rolling backwards, and you throw a ball forwards. You have to throw the ball harder to make it go X feet (meters/metres/cubits/whatever), compared to when you are standing still when you throw it. Now if the air molecules are moving away at > mach 1, then the sound will never reach you, since the molecules are moving away more distance per unit time than the pressure wave is approaching you. --Mike-- Ericahist | CP SearchBar v2.0.2 | Homepage | RightClick-Encrypt | 1ClickPicGrabber Kosh reminded me of some of the prima-donna programmers I've worked with. Knew everything but when you asked them a question; never gave you a straight answer. -- Michael P. Butler in the Lounge
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greba wrote: would the sound have a harder time of reaching the upwind reciever Yes, because sound is actually a pressure wave moving through the air. It requires one air molecule to bang into the next, transferring kinetic energy to make it bang into the next... and so on. If those molecules are all moving away from you at the same time all that is happening, it will take longer for the wave to reach you, which also means the sound has to have more energy (ie, be louder at the source) to reach you. Think of an analogous situation - you're in a chair with rollers and rolling backwards, and you throw a ball forwards. You have to throw the ball harder to make it go X feet (meters/metres/cubits/whatever), compared to when you are standing still when you throw it. Now if the air molecules are moving away at > mach 1, then the sound will never reach you, since the molecules are moving away more distance per unit time than the pressure wave is approaching you. --Mike-- Ericahist | CP SearchBar v2.0.2 | Homepage | RightClick-Encrypt | 1ClickPicGrabber Kosh reminded me of some of the prima-donna programmers I've worked with. Knew everything but when you asked them a question; never gave you a straight answer. -- Michael P. Butler in the Lounge
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greba wrote: would the sound have a harder time of reaching the upwind reciever Yes, because sound is actually a pressure wave moving through the air. It requires one air molecule to bang into the next, transferring kinetic energy to make it bang into the next... and so on. If those molecules are all moving away from you at the same time all that is happening, it will take longer for the wave to reach you, which also means the sound has to have more energy (ie, be louder at the source) to reach you. Think of an analogous situation - you're in a chair with rollers and rolling backwards, and you throw a ball forwards. You have to throw the ball harder to make it go X feet (meters/metres/cubits/whatever), compared to when you are standing still when you throw it. Now if the air molecules are moving away at > mach 1, then the sound will never reach you, since the molecules are moving away more distance per unit time than the pressure wave is approaching you. --Mike-- Ericahist | CP SearchBar v2.0.2 | Homepage | RightClick-Encrypt | 1ClickPicGrabber Kosh reminded me of some of the prima-donna programmers I've worked with. Knew everything but when you asked them a question; never gave you a straight answer. -- Michael P. Butler in the Lounge
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Was lying in bed last night with the fan and the radio on, when a physics problem came into my mind. In a wind tunnel you have source of sound, speaker, and a few listeners positions upwind and downwind of the speaker. Assuming the speaker is loud enough over the volume of the wind/fan, would the sound have a harder time of reaching the upwind reciever compared to the downwind reciever? In other words, If you got the wind speed up or even past the speed of sound would the reciever upwind hear nothing, and the downwind reciever here everything? :confused::confused::confused: Greba, My lack of content on my home page should be entertaining.
One thing to keep in mind is air in general acts like a low pass filter. For instance, a jet plane far away sounds very low pitched, but when you're close to the engine, there's plenty of treble.
I, for one, do not think the problem was that the band was down. I think that the problem may have been that there was a Stonehenge monument on the stage that was in danger of being crushed by a dwarf.
-David St. Hubbins -
greba wrote: would the sound have a harder time of reaching the upwind reciever Yes, because sound is actually a pressure wave moving through the air. It requires one air molecule to bang into the next, transferring kinetic energy to make it bang into the next... and so on. If those molecules are all moving away from you at the same time all that is happening, it will take longer for the wave to reach you, which also means the sound has to have more energy (ie, be louder at the source) to reach you. Think of an analogous situation - you're in a chair with rollers and rolling backwards, and you throw a ball forwards. You have to throw the ball harder to make it go X feet (meters/metres/cubits/whatever), compared to when you are standing still when you throw it. Now if the air molecules are moving away at > mach 1, then the sound will never reach you, since the molecules are moving away more distance per unit time than the pressure wave is approaching you. --Mike-- Ericahist | CP SearchBar v2.0.2 | Homepage | RightClick-Encrypt | 1ClickPicGrabber Kosh reminded me of some of the prima-donna programmers I've worked with. Knew everything but when you asked them a question; never gave you a straight answer. -- Michael P. Butler in the Lounge
To nit pick a little that would fail unless the wind tunnel is infinitely wide. Some noise will make it to the walls and then travel along them. So yes the noise would not make it directly in the air but if loud enough or the receiver is sensitive enough some would be heard. Also most wind tunnels circulate around a path. So you do not have to impart all the energy at once to "bring it up to speed." But I do not think those were what was being asked. :rolleyes: "For as long as I can remember, I have had memories. Colin Mochrie."
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Thanks, I thought that was the answer. Now all I need to do is get a fan capable of producing mach wind speeds.;) Greba, My lack of content on my home page should be entertaining.
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greba wrote: would the sound have a harder time of reaching the upwind reciever Yes, because sound is actually a pressure wave moving through the air. It requires one air molecule to bang into the next, transferring kinetic energy to make it bang into the next... and so on. If those molecules are all moving away from you at the same time all that is happening, it will take longer for the wave to reach you, which also means the sound has to have more energy (ie, be louder at the source) to reach you. Think of an analogous situation - you're in a chair with rollers and rolling backwards, and you throw a ball forwards. You have to throw the ball harder to make it go X feet (meters/metres/cubits/whatever), compared to when you are standing still when you throw it. Now if the air molecules are moving away at > mach 1, then the sound will never reach you, since the molecules are moving away more distance per unit time than the pressure wave is approaching you. --Mike-- Ericahist | CP SearchBar v2.0.2 | Homepage | RightClick-Encrypt | 1ClickPicGrabber Kosh reminded me of some of the prima-donna programmers I've worked with. Knew everything but when you asked them a question; never gave you a straight answer. -- Michael P. Butler in the Lounge
Now... that brings up a good point... how the heck do you have a mass of air rush past you at the speed of sound with little or no turbulence so you can test this theory. Maybe in your wind tunnel have a bunch of pressurized pin holes feeding air into the wind tunnel. heh -- Marc Life is too short to program in Visual Basic.