If bullets go faster than the speed of sound, then why don't they create sonic booms?
356537
They do.\n\n(It bears mentioning at this point that there is such a thing as subsonic ammunition.)\n\nWhen something moves through the sound barrier (accelerates to beyond the speed of sound,) it creates a conical pressure wave that travels some distance behind.  The distance increases between the object and the face of tis pressure wave increases as velocity increases.\n\nThe size of this pressure wave is roughly governed by the size of the object.  Therefore, aircraft make very loud "sonic booms" whereas bullets tend to make a slight popping-whining sound as they travel past you.\n\nThe noise is, believe me, rather unnerving.
887565
Sound travels at different speeds depending on what it is traveling through. Of the three mediums (gas, liquid, and solid) sound waves travel the slowest through gases, faster through liquids, and fastest through solids. Temperature also affects the speed of sound. \nGases: \n\nThe speed of sound depends upon the properties of the medium it is passing through. When we look at the properties of a gas, we see that only when molecules collide with each other can the condensations and rarefactions of a sound wave move about. So, it makes sense that the speed of sound has the same order of magnitude as the average molecular speed between collisions. In a gas, it is particularly important to know the temperature. This is because at lower temperatures, molecules collide more often, giving the sound wave more chances to move around rapidly. At freezing (0º Celcius), sound travels through air at 331 meters per second (about 740 mph). But, at 20ºC, room temperature, sound travels at 343 meters per second (767 mph). \n\nLiquids: \n\nSound travels faster in liquids than in gases because molecules are more tightly packed. In fresh water, sound waves travel at 1,482 meters per second (about 3,315 mph). That's well over 4 times faster than in air! Several ocean-dwelling animals rely upon sound waves to communicate with other animals and to locate food and obstacles. The reason that they are able to effectively use this method of communication over long distances is that sound travels so much faster in water.\n\nSolids: \n\nSound travels fastest through solids. This is because molecules in a solid medium are much closer together than those in a liquid or gas, allowing sound waves to travel more quickly through it. In fact, sound waves travel over 17 times faster through steel than through air. The exact speed of sound in steel is 5,960 meters per second (13,332 mph)! But, this is only for the majority of solids. The speed of sound in all solids are not faster than in all liquids
756089
The question asks nothing about the speed of sound in air compared with water. I believe that the answer is that sound will travel farther through air than water. \n\nMy reasoning is as follows:\n\nSound is a compression wave and its propagation is based upon atoms and/or molecues "bumping into" each-other in order to convey the energy of the sound. Now, with each collision between atoms/molecules, some energy is lost due to heat, so the more collisions there are (eg water), the more energy is lost. The fewer collisions there are (eg air) the less energy is lost. Of course, as everyone has pointed out, water is more dense than air, so there are more collisions per metre in water than in air, and so more energy loss per metre in water than in air.\n\nTherefore sound will travel farther in air than in water. \n\nAnother way to look at it is by taking it to the extreme. Let us imagine for a moment that there is a lonely molecule in outer space and we "bump" it with a spaceship. It will travel through space unimpeded, carrying that energy until it finds another molecule to bump into, maybe millions of kilometres away. So, that energy the spaceship imparted onto that molecule has travelled millions of kilometres. We can't hear a single molecule hitting our eardrums, but the effect is the same.\n\nAnyway, I hope that analogy helps.
519370
Well. they are still sound and still have to comply with all the laws that apply to sound.\nThe reason we cannot hear them is our ears cannot pick up such high frequency sound.\nBats can hear ultrasound and this is probably why you never see bats in a hospital.. They wouldn't know which way to turn.\nBecause ultrasound has a short enough wavelength it is able to pass through certain things. This is because the wavelenth is of an order of magnitude similar to the molecular spacings in the object is is being "beamed" into.\n\nObviously they are absorbed by objects, like your internal organs otherwise they'd be of absolutely no use whatsoever for us.... When I say absporbtion I also mean reflection and refraction. \n\nThey can travel undeviated if the microwaves are collimated "turned into a focused beam" rather like X rays.
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.
300281
Sound travels through the air at about 330 meters/second.  Kids have been taught for years in Scouts that it takes 5 seconds for a the sound of a lightning-generated thunderclap to travel a mile.  It doesn't take very sophisticated electronics to generate a sound pulse, simultaneously start a clock, and measure the time it takes for the sound to bounce off its target and return.  Real estate agents for years have used a small device that does this to measure room sizes.  Limiting factors are the distance to be measured and the amount of sound reflected.
235514
The slowest muzzle velocity ammo is faster than the speed of sound, add reaction time of deer to it, no. Multiple shots possibly afford some escape time.
1174955
In outer space there are some gasses but not enough in any one place to provide a medium for a sound wave to propagate through. Asteroids and meteors are silent until they enter an atmosphere.
426415
In theory yes, but what is going to generate the sound?  It would have to be very loud for it to be practical.
278787
in waves, therefore, in order to be transmitted it requires some medium to transmit the waves in. That's why sound can't travel through a vacuum such as outer space, for example
404601
Mechanical energy can only be transferred at the speed of sound.  For example in a massive star when it ends it's iron burning, the core pressures will suddenly over come electron degeneracy pressures and go into a free fall.  The inner part of the core will actually cross the speed of sound as it collapses and the outer burning shells will not "know" the core is collapsing and continue to fuse until the shock wave from the core travels out to it.
340667
Again, the speed of light is a constant!  It does not increase in speed of the flashlight is moving really fast.  Its' like sound, sound goes 700mph in air at sea level.  If the plane goes faster than that it catches the sound, the sound doesn't go faster in front of the plane.  Same with light. Same with the opposite direction.
365737
Assuming you fire parallel to the ground, then the bullet will be at its maximum horizontal velocity when it leaves the barrel, and will be at minimum vertical velocity.  The bullet cannot increase in horizontal speed once it has left the barrel, as there is nothing to make it accelerate.\n\nDue to air resistance, the horizontal velocity will decrease as the bullet travels further and further.  The vertical velocity will increase, as the gravity of the Earth "attracts" the bullet.
1074897
absolutely, the military is working on one right now for there new electric battleship (in 2011). However, a railgun doesn't use heat to accelerate a projectile and the heat is just a sideeffect. a rail gun uses two electricaly charged superconductive rails, hence the name, to creat a super strong magnetic field around the armerture to fire the slug. The slug is made from DU(depleted uranium) or tungragen so it woudn't turn into a beam. Real railguns have the distructive energy as a small nuke without the radiation and complex dilivery system. a cheap 40 kilogram (about 75 pounds) can vaporize a target 600 miles away in a few minutes. the barral volocity is many times that of a regular gun and can be as high as Mach 9
592273
Probably a similar thing to that which happens when you reach the sound barrier.  I'm sure the light particles/energy build up and will create an explosion.
929509
Assuming they have exact amounts of energy, at the exact same direction, Gravity would have pulled them ever so slightly downwards. The impact would generate a large amount of heat, and the bullets would rebound and continue on their descent downwards to the ground. (assuming they did not have enough heat to fragment or melt)\n\nIn practice, one bullet hits the other bullet slightly higher than the other, causing one bullet to fly upwards in the air back from where it was fired, and the other to fall downwards back to where it was fired.
1140623
maybe someone got shot right outside your window while it was raining.. perfect cover\n\nNo, really the different sounds are created by different frequencies and wavelentghs of the vibrations caused by the electricity splitting the air. This can vary from the sonic boom you hear when a F15 crosses Mach 1 .. to the crack noise you hear with a whip. As for the loudness, it is a function of intensity and proximity.. so yea the same lightning will be louder when its closer.. but it could also be a very strong lightning far away.. the way you could tell would be the difference in light and sound... \n\ni hope this helps