A factory siren emits a steady note while mounted on a tower beside a lake.
(a) The frequency of the note is 2.5kHz. Express this frequency in hertz.
(b) Taking the speed of sound in air to be 340m/s, calculate the wavelength of the sound in air.
(c) The same sound travels across the lake surface and then enters water where its speed becomes 1500m/s. For the same frequency, determine the wavelength of the sound in water.
(d) Compare the answers of parts (b) and (c) and state one reason for the difference observed.