🔴 Source velocity
0.0 v/c
Fraction of wave speed · Positive = rightward
🔵 Observer velocity
0.0 v/c
Fraction of wave speed · Positive = rightward
🟢 Source frequency
2.0 Hz
Emission frequency of source
Physical principles
- Wave speed v in the medium is constant regardless of source or observer motion
- Source motion compresses wavefronts (blue-shift) or stretches them (red-shift)
- Observer moving toward source increases wavefront encounter rate
- Velocities are normalised: slider value = fraction of wave speed v
- When |vs| ≥ v, a Mach cone shock wave forms (shown in gold)
Sign convention & formula
- vs > 0: source moves rightward (toward observer if obs is right)
- vo > 0: observer moves rightward (away if src is left)
- Theoretical: fobs = f₀ · (v + vo) / (v − vs)
- Wavelength: λ = (v − vs) / f₀
- Mach number: M = |vs| / v — cone half-angle = arcsin(1/M)