Sonic boom physics

Sound travels about 330 m/s (740 mph) in the atmosphere. When an object is travelling slower than the speed of the sound waves being generated, the sound waves radiate out in all directions, as shown below.

But, when an object is travelling faster than the speed of sound, the object passes by a point before the sound does. The sound continues to spread out behind the object, but all the sound in front of the object is concentrated into a sharp cone. This cone is the sonic boom.

Sound is related to pressure, and sonic booms can produce pressures over 1 mb (the atmospheric pressure is close to 1000 mb). So, the pressure increase (equal to about 0.015 psi) is what produced the shaking of our roofs, windows, etc. 0.015 psi doesn’t sound like much, until you think about your house, if it is, say, 1,500 square feet, suddenly felt an extra 3,000 pounds of air pressure as the sonic boom went overhead.

Aircraft with sonic boom.

Category: Pre-November 2010 Posts