Question

What would happen to the speed of a sound wave if it moved from ocean water to air?





What would happen to the speed of a sound wave if it moved from a cooler room to a warmer one?

Answer 1

- From ocean water to air: the speed drops. Sound travels much faster in water (~1500 m/s) than in air (~340 m/s at room temperature) because v in a fluid is v = sqrt(B/ρ) (B = bulk modulus, ρ = density) and water’s stiffness is far larger than air’s. The wave’s frequency stays the same at the boundary but its wavelength changes (λ = v/f), and most energy is reflected at the water–air interface because of the large acoustic-impedance mismatch.

- From a cooler room to a warmer room: the speed increases. In a gas v ≈ sqrt(γR T/M) so v ∝ sqrt(T) (absolute temperature). A common approximation is v ≈ 331 + 0.6·T(°C). For example, sound is ≈337 m/s at 10 °C and ≈349 m/s at 30 °C, so it gets faster as the air warms.