would a plane with a perfectly silent engine produce a sonic boom?
396057
Yes.  Sonic booms occur when the air in front of a body moving faster than the speed of sound becomes very compressed and shockwaves cause a loud boom.\n\nA shuttle gliding to Earth is travelling without its engines operating.  Yet, it still produces a sonic boom.  People living near Space Shuttle landing sites will confirm this; and hence answer your question.
67597
Yes, this the way airplanes used to distribute sound. The quality was not bad. You listened to it with headphones.
37371
yes, just because nobody hears it doesnt mean it wont make a sound.
897794
Absolutely! I'm surprised you can't hear the diff. It throws off the entire vibration structure, but I suppose some might like it that way.
1122190
There would always be some sound, however imperceptible from the natural motions of the gases of the air, even if no percussion were present.
280985
well it wouldn't BE the computer that generates it, but rather a device attached that would emit those frequencies.\n\nspeakers won't....no point in designing sound range capability that is, by definition in-audiable.\n\nthough I guess if you were to modify a hard drive you could creat freqs in that range....though how to confirm it....?
860346
When going uphill (acceleration) and returning to Earth (deceleration), the shuttle passes the speed of sound 1 time each.  The boom that you hear is the release of the air pressure that has built up (in the form of a cone around the aircraft).  There are actually two "booms"; 1 when the craft's nose passes beyond the pressurized cone, and 2 when the tail of the craft passes beyond the pressurized cone.\n\nOn smaller aircraft the two booms generally cannot be distinguished separately so we just refer to them as one sonic boom.  On the space shuttle however, because it is a much bulkier craft, the two booms are distinguished easily.\n\nSo during ascent and descent there are 2 sonic booms each.  Once when the nose passes the pressure cone and second when the tail passes the pressure cone.
173806
A jet engine is around 120db from 25 meters away, sorry i don't know conversion for miles.  I used to have a car stereo for competition and it would produce 152.4db if thats any help.  The bass can travel easily the distance you are talking about.  Permanent hearing loss starts at 90db so its most likely even with hearing protection he will still go deaf as he practically is sitting in a speaker box.  As for the volume going up its probably because he is already going deaf so has to turn it up, and on cold days when the air is more dense it will actually be up to an extra 3db louder, and also depending on wind direction.  Does this help?, in aus you can be fined for excessive car stereo noise! and even have your car confiscated!
1134088
It would have to be extremely high-pitched (probably over 25,000 cycles per second). Are telephone speakers able to generate such a high pitch? Probably not, as that would drive up the cost of the phone a lot.
274345
in fact it can....but it pales in comparison to the sound you hear in space when a large f-650 diesel rumbes through the grove on a fine sunday  afternoon
115074
No...there needs to be a medium for sound to travel through, considering the Big Bang was the beginning, there would be no 'ether' for any sound waves. Just as we cannot hear any of the large energy bursts from the sun which occur everyday.
871918
only in space where there is no air\n\nof  course there no clouds either but electrical spark can still be produced artificially\n\nedit: "a mile away for every second counted: -- make this about 4-5 seconds; the sound speed is about 300m/s
342
If the plane is on a treadmill like the ones we run on at the gym, then it won't really be 'going' anywhere and will not take off because no air is passing by the wings to generate lift.  \n\nI think you might have to clarify this one further...
1159509
It is fairly easy to silence a firearm but understand you can truly only silence a bullet that is traveling less than the speed of sound.  Any bullet traveling faster than that has it's own sonic boom which sounds like a crack down range.  That you cannot silence.  Sub-sonic cartridges are designed for slower velocities which will allow for true silencing.  At sea level, I believe the speed of sound to be around 750 miles per hour which translates to ~1100 feet per second.  The rest of the answers are true enough... just like adding a muffler.
548339
Horse power can be used for both it is a value given to the amount of energy needed to perform (x) amount of work per second.\n  I believe you are more interested in thrust, which is the forward propulsion of the jet engine.  \n  That would go more towards ft/lbs.  \n\nOne extra little known tid bit.  The super jet engines like on the C-5 military transport uses some water injection on take off.  This is what causes the dark exhaust you see. \n\nIf I remember correctly when water flashes to steam it has a 1:26 pressure expasion rate.  \nAs you can see this has a significant impact on the amount of thrust for the engine as well as a cooling effect.\n\nAnd of course the lift is all by design of the wing.  If you took the wings off of a plane it would never get off the ground...  \n\n    But it would make one fast car !!!
394921
Sound does not travel in a vacuum.
1078650
The pulsating flow from each cylinder's exhaust process of an automobile petrol or diesel engine sets up pressure waves in the exhaust system-the exhaust port and the manifold having average pressure levels higher than the atmospheric. This varies with the engine speed and load. \nAt higher speeds and loads the exhaust manifold is at pressures substantially above atmospheric pressure. These pressure waves propagate at speed of the sound relative to the moving exhaust gas, which escapes with a high velocity producing an objectionable exhaust boom or noise. \nA suitably designed exhaust silencer or muffler accomplishes the muffling of this exhaust noise. The basics of silencing can be understood by recalling a few principles of physics. The velocity of sound in the gas at a given temperature is directly proportional to the square root of the product of the pressure and the ratio of the specific heats (at constant pressure to that at constant volume), and inversely to the square root of the density of the gas. \nAs the temperature varies, the velocity also varies directly as the temperature by another square root law involving the product of the coefficient of thermal expansion of the gas and the temperature. The exhaust noise can be reduced appreciably by providing resonance chambers to offset the noise wave effects. Since it silences the noise to be produced by the exhaust air . it is called silencer.