A sound wave travels in air toward the surface of a freshwater lake and enters into the water. The frequency of the sound does not change when the sound enters the water. The wavelength of the sound is 3.52 m in the air, and the temperature of both the air and the water is 20 oC. What is the wavelength in the water?

Pls help!

3 answers

distance = speed * time
here time is the period, T, which is 1/f and constant if f is constant which they did not have to tell us because we know there is no place to store extra waves.
distance is the wavelength or how far it goes in time T
so
lambda = V T
3.52 = Vair T
so
T = (3.52/Vair)
same T in water so
(3.52/Vair) = x / Vwater
solve for x
What do I use as the speed of water and air?
Va = 330 m/s.
Vw = 1490 m/s.

3.52 = Va/F
3.52 = 330/F,
F = 93.75 Hz.

Wavelength = Vw/F = 1490/93.75 = 15.89 m.