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The World Motor Sport Council homologated the new world land speed records set by the team ThrustSSC of Richard Noble, driver Andy Green, on 15 October 1997 at Black Rock Desert, Nevada (USA). This is the first time in history that a land vehicle has exceeded the speed of sound. The new records are as follows:
The speed of sound is the distance travelled per unit of time by a sound wave as it propagates through an elastic medium. More simply, the speed of sound is how fast vibrations travel. At 20 °C (68 °F), the speed of sound in air, is about 343 m/s (1,125 ft/s; 1,235 km/h; 767 mph; 667 kn), or 1 km in 2.91 s or one mile in 4.69 s.
The creation of the sonic boom was confirmed in 1958 [1] by analyzing the high-speed shadow photography taken in 1927. [ 2 ] [ 3 ] Recently, an additional, purely geometrical factor was recognized: the tip of the whip moves twice as fast at the loop of the whip, just like the top of a car's wheel moves twice as fast as the car itself.
However, unlike the spacetime metric, in which the invariant speed is the absolute upper limit on the propagation of all causal effects, the invariant speed in an acoustic metric is not the upper limit on propagation speeds. For example, the speed of sound is less than the speed of light.
In this instance, heavier bullets are loaded in standard ammunition, which reduces muzzle velocity below the speed of sound. As an example, the very common 9×19mm Parabellum standard military round is a 7.5 g (116 gr) bullet at velocities typically around 360 m/s (1,200 ft/s). Subsonic loads for 9×19mm Parabellum commonly use 9.5 g (147 gr ...
The sound barrier or sonic barrier is the large increase in aerodynamic drag and other undesirable effects experienced by an aircraft or other object when it approaches the speed of sound. When aircraft first approached the speed of sound, these effects were seen as constituting a barrier, making faster speeds very difficult or impossible.
On 15 October 1997, 50 years and 1 day after the sound barrier was broken in aerial flight by Chuck Yeager, Green reached 763.035 miles per hour (1,227.986 km/h), the first supersonic record (Mach 1.016). His call sign was "Dead Dog". As the vehicle exceeded the speed of sound it created a sonic boom.
Those physical properties and the speed of sound change with ambient conditions. For example, the speed of sound in gases depends on temperature. In 20 °C (68 °F) air at sea level, the speed of sound is approximately 343 m/s (1,230 km/h; 767 mph) using the formula v [m/s] = 331 + 0.6 T [°C].