Shock Wave and Mach Cone (Sonic Boom)

Theory

When the source moves faster than the waves ($v_s>v$), wavefronts pile up on a cone — the shock wave. The half-angle of the Mach cone satisfies $\sin \alpha =\frac{v}{v_s}=\frac{1}{M}$, where $M=v_s/v$ is the Mach number.

What to observe

• At Mach 1.5 the cone half-angle is ≈ 42°.
• No sound reaches the listener ahead before the source itself.

Try this

• Set vₛ = v (Mach 1): the fronts stack into a wall — the “sound barrier”.
• Increase vₛ: the cone gets narrower.

Also available in: Onda de choque e cone de Mach (estrondo sônico) (Português) · Onda de choque y cono de Mach (estampido sónico) (Español)