What casues a sonic boom and how fast do you need to be going to cause one?

Question

how fast would a plane traveling at normal transportation altitude need to be going to cause a sonic boom?

Answer 1

It would have to suurpass  the speed of sound.

The speed of sound (otherwise known as Mach 1) varies with temperature. At sea level on a “standard day,” the temperature is 59°F, and Mach 1 is approximately 761 mph. As the altitude increases, the temperature and speed of sound both decrease until about 36,000 feet, after which the temperature remains steady until about 60,000 feet. Within that 36,000–60,000 foot range, Mach 1 is about 661 mph. Because of the variation, it is possible for an airplane flying supersonic at high altitude to be slower than a subsonic flight at sea level.

The transonic band (the “sound barrier”) extends from around Mach .8—when the first supersonic shock waves form on the wing—to Mach 1.2, when the entire wing has gone supersonic.

A sonic boom is the thunder-like noise a person on the ground hears when an aircraft or other type of aerospace vehicle flies overhead faster than the speed of sound or supersonic.

Air reacts like a fluid to supersonic objects. As objects travel through the air, the air molecules are pushed aside with great force and this forms a shock wave much like a boat creates a bow wave. The bigger and heavier the aircraft, the more air it displaces.

Answer 2

Sonic boom is an impulsive noise similar to thunder. It is caused by an object moving faster than sound, about 750 miles per hour at sea level. An aircraft traveling through the atmosphere continuously produces air-pressure waves similar to the water waves caused by a ship's bow. When the aircraft exceeds the speed of sound, these pressure waves combine and form shock waves which travel forward from the generation or "release" point.  As an aircraft flies at supersonic speeds it is continually generating shock waves, dropping sonic boom along its flight path, similar to someone dropping objects from a moving vehicle. From the perspective of the aircraft, the boom appears to be swept backwards as it travels away from the aircraft. If the plane makes a sharp turn or pulls up, the boom will hit the ground in front of the aircraft. The sound heard on the ground as a "sonic boom" is the sudden onset and release of pressure after the buildup by the shock wave or "peak overpressure." The change in pressure caused by sonic boom is only a few pounds per square foot, about the same pressure change we experience on an elevator as it descends two or three floors, in a much shorter time period. It is the magnitude of this peak overpressure that describes a sonic boom.

Answer 3

761mph and if you want to read about it go to

http://en.wikipedia.org/wiki/Sonic_boom

Answer 4

A sonic boom is caused by a pressure differential caused by compressability of air near the speed of sound, in other words the air cant get out of the way quickly enough, and it causes a wave f pressure to build up. As the aircraft goes faster than the speed of sound the pressure gradually spreads over the length of the aircraft and the gradient of the wave becomes much less. It actually takes more energy to break the sound barrier than it does to cruise faster than it. The sound barrier increases air friction to up to 10 times normal between mach 0.7 and 1.4, and then goes back to normal. If an aircraft can break mach 1 it almost certainly can reach mach 1.7. If you look around at most fighter aircraft, they are either subsonic or they can sustain faster than mach 1.7, there are very few that cant. There is is a gap from mach 0.9 until mach 1.7, nearly no aircraft that have maximum speeds in that range.

The speed of sound differs with pressure altitude, which accounts for ambient pressure and temperature.

Certain aircraft have whats called a supercritical wing, which means that the air over the top of the wing can sustain supersonic speed while it is subsonic underneith. This can cause a sonic boom at much lower speed than mach 1, possibly as low as mach 0.6.