Calculate frequency using wave speed formula

Steps:

• Measure wavelength λ from diagram as distance between consecutive compressions (λ = 0.395 m).
• Recall wave speed v = 340 m/s.
• Apply formula f = v / λ.
• Compute f = 340 / 0.395 = 860 Hz.

Why B is correct:

• 860 Hz equals v / λ per the wave equation f = v / λ, defining frequency as speed divided by wavelength.

Why the others are wrong:

• A: 430 Hz implies λ = 0.79 m, double the diagram's wavelength.
• C: 1100 Hz implies λ = 0.31 m, shorter than diagram.
• D: 1400 Hz implies λ = 0.24 m, much shorter than diagram.

Final answer: B