how come a sound is not heard when a pendulum moves?
494299
Because your ears aren't sensitive enough\nbut actually if they are sensitive enough, u can hear it.
632971
No, but it probably feels vibrations, which is kinda like hearing.  Snakes don't have ears, but they "hear" vibrations.
534293
To hear a noise you need to have something for the noise to propagate through. The sun and Mercury exist in the vacuum of space. There is nothing in a vacuum, hence no sound can travel. So no, we can't hear the noise the sun or mercury make. Sound won't travel through the vacuum of space.\n\nBut the sun certainly makes a noise, it is after all a massive fusion reactor. If you could stand within the atmosphere of the sun without being vaporised or crushed you would be deafened by the noise it makes.\n\nBut once you left the Sun's atmosphere the noise would stop. All of space is a vacuum and totally silent.
703678
Two techniques: analog and digital.\nAnalog: the sound is a variation of air pressure.  This variation is "measured" by a microphone (or similar), to convert the pressure differences into variations of voltage.\nThis voltage variation is then used, after amplification, to act upon a "stylus" (in the case of Edison) that "vibrate" on a cylinder of soft wax, animated by a rotation and a horizontal translation.  The variations of the stylus can be read afterwards by retarting the process, this time fromt the stylus to a speaker.\nLater, the voltage variations where converted in magnetic variations that were "written" to a wire first, then to a tape (tape recorders).\nNowadays, the same voltage variations are "sliced" and measured many times per second, converted in numeric value, and it is the number that is recorded on some disc or solid state memory: this is the digital recording.
409841
They did this on mythbusters, episode 8.   I can't exactly remember why you can't hear it, but it does echo.  I think the echo came back so fast, you still heard it when you were hearing the origonal quack.
1128070
Music is organized sound, so I think the answer would be "irregular vibration patterns".  These links should help.
1148570
Wind means flow of air mass from one place to another place. That makes no sound waves. But when it strikes our ear it is obstructed and pressure varries.\n\nBut if during its flow if the pressure of air varies; the variation is sound wave. If the frequency of sound wave is in the audible range we hear  the sound. \n\nObstacles like buildings trees etc. make the pressure variations; and sound is heard. \n\nIn a room, if the fan is made to rotate very slowly, gentle flow of air can be felt with no sound.
419821
must be some kind of a transducer. it could also be a laser as i am not sure whether it is sound or light waves. i think it will use a laser and a sensor to detect the reflaction and hence how near it is to an object.
713824
Sonority is the quality of being resonant.  A metal tuning fork can produce a steady tone because when energy is added by striking it, it vibrates with little loss of energy.  If you strike a lump of wet clay the energy is quickly lost with no sustained vibration.  A metal rod or bell can produce tones because the metal vibrates in lengths corresponding to the fundamental and higher overtones of sound waves that also travel as lengths of air disturbance (rarefactions and condensations).  Actually ordinary bells do not produce the fundamental tone which is why they sound "bell-like."
918346
that is an ancient question like Which came first, Chicken or Egg.  Nobody knows that answer for sure.\nI believe it does not make noise, as noise is something that is created inside the head which has ears that interpret the vibrations as sound.  No ears, no sound.\nClarkie's theory on Tree Noise.
411063
no: If no one hears it, it doesn't because sound is only vibrations in the air if our ear drums don't hear it.
832001
YES!!!\n\nPhysically, yes it makes a sound, sound does not need someone to be present for it to exist.  If you're looking for some philosophical answer, this is not the place to ask it.
1178452
The velocity of sound in air or the frequency of a tuning fork is determined using the principle of resonance of air column.\n\nIn that experiment the length of air column is adjusted and the tuning fork is used to vibrate the air column; the water or glass is not vibrating so much and can be considered as having no vibration at all. \n\nWhen the frequency of tuning fork is high the resonating length of air column is less.\n\nHere in your case, the water and hence the glass are vibrating, and sound is passed through the air. No stationary sound wave is formed above the water level.\n\nThis is a case of forced vibration and the vibration frequency depends only upon the vibration of water particles, the glass vibrates with the frequency of the water particles; the glass is not left free to vibrate with its natural frequency.\n\nIf you have water to some level in the glass and strike the glass with some hammer and leave it to vibrate then only the glass will vibrate with its natural frequency.
974804
It won't work.  You can look at it this way:\n\nOne of the basic laws of physics is Conservation of Energy.  You can't create energy, nor is energy lost.  It is always constant, but it may change form.  Let me give several examples.\n\nThe energy associated with a swinging pendulum changes from kinetic (moving) energy at the bottom of the swing to potential energy at the top of the swing.  Back and forth, kinetic energy, potential energy, kinetic energy, potential energy, etc.  The swing of the pendulum does slowly die down, but that is due to the gradual transfer of kinetic energy to the surrounding air in the form of heat.\n\nIn the second example, the kinetic energy of a moving car is converted to thermal energy (heat) when you hit the brakes.  That's why your brakes get hot if you've been doing a lot of braking.  Of course, to get the car moving in the first place, the engine converts chemical energy from gasoline to thermal energy, which expands the gases in the pistons, pushing on the pistons to make the mechanical energy that turns the wheels.\n\nBack to your problem.  To charge a battery, the energy must come from somewhere.  The amount of energy coming from your voice is small, and certainly the amount of energy picked up by a microphone is much smaller, since most of the energy goes right on past the microphone.  It would take a very strong voice and a lot of talking to charge a battery, even if the charging circuit were perfect with no losses.\n\nNow, if your voice could turn a windmill.........
49424
Not neccessarily.  But it is not because the sound waves are being affected by gravity.  It is because the medium that the sound travels through is affected by gravity.  The air is thicker at the 1st floor and thinner at the 10th floor.  To make an extreme example it would be like passing sound through water at the 1st floor and air at the 10th.  So yes it will be different sounds but because of the effect of gravity on the medium not the waves.
879231
The simple pendulum requires a massless connection between the pivot and the oscillating mass.  Also, the mass must be concentrated at one discrete radius (can have no radial thickness).  Add air and pivot drag to these and you essentially have the difference between theory & reality........
588650
No we can hear them.  We may go deaf, but we can hear them.  What we can't hear is very very very high pitched or very very very low pitched sounds.  The higher it goes the louder it seems even tho the sound intesity has not changed.  The lower, the quieter.  IT has to do with the physics and chemistry of your ear drum and the way the hammer (forgot the actual term, sorry) strikes the drum of your ear.