In the figure above we can see the formation of shock waves. These waves are mechanical waves with high frequency and energy density.
The figure above shows us an airplane that travels at the same speed as sound, so we can see that the airplane is traveling at the same speed as the waves produced by it. Thus, the circles tangent to the same point, where all the wavefronts add up and the disturbance in the middle becomes very large, resulting in a shock wave.
In the figure below we can see that for an airplane that flies faster than the speed of sound, the wave crests form a series of arranged circles. We have the formation of a cone when we draw tangent lines to the circles.
For an observer who is situated at a point outside the region covered by the circles, no sound will be detected. But when the region encompassing the circles passes through the observer, he will feel a sudden change in pressure, as if it were a small explosion, or a shock wave.
Shock waves produced by an airplane flying faster than the speed of sound.
The speeds of supersonic planes are measured as a function of the sound in the medium. In honor of physicist Ernst Mach, this speed is called mach 1. Thus, we say that when a plane flies at the speed of sound, it has mach 1. If you are flying with mach 2, we can say that this plane flies at a speed twice the speed of sound.
In fact, we cannot accurately determine (unless we know what the speed of sound is at that point) the speed in km/h or in m/s because there is variation in temperature and density of the quite. An airplane, flying in mach 1, at a great height, will certainly be flying at a speed lower than 340 m/s, that is, at 1,224 km/h, since the air density decreases with altitude.
By Domitiano Marques
Graduated in Physics
Brazil School Team
waves - Physics - Brazil School