LO8

1. Wave Propagation and the Sonic
Boom

2. What is a sonic boom?
Sonic boom: A loud noise caused by the shock
wave created when an aircraft surpasses the
speed of sound (340.29m/s).
Shock waves such as this can also be created from
explosions as seen in the image below.

3. How is a sonic boom created?
• A sonic boom is produced when the sound waves
created by the aircraft can no longer travel fast
enough to propagate away from the plane ahead of
its flight.
• A sonic boom is a shock wave

4. Shock Waves
• Shock Wave: A wave that moves faster
than the speed of sound in a medium.
• Just before the speed of sound is
reached the wave fronts of sound waves
“pile up” in front of the object this is the
sound barrier.
• When the speed of a source exceeds
the speed of sound and the wave fronts
trail behind the source.
• This creates a conical wave (the shock
wave) that fans out behind the object.

5. Did you know??
• It is very dangerous for pilots to fly at the speed of sound
because of the “sound barrier.”
– A piling up of waves in front of the aircraft.
• The sound barrier is a drastic increase in drag and other
aerodynamic effects when an object approaches the sound
barrier.
• This can make
an aircraft
difficult to steer
and/or
accelerate.