A boat is traveling in a river with a speed 10 m/s along the stream flowing with a speed 2 m/s . From this boat, a sound transmitter is lowered into the river through a rigid support. The wavelength of the sound emitted from the transmitter inside the water is 14.45 mm . Assume that attenuation of sound in water and air is negligible.
(Temperature of the air and water = 20∘C ; Density of river water = 103 kg/m3 ; Bulk modulus of the water = 2.088×109 Pa ; Gas constant R=8.31 J/mol-K ; Mean molecular mass of air = 28.8×10−3 kg/mol ; Cp/Cv for air = 1.4)
(a) What will be the frequency detected by a receiver kept inside the river downstream?
(b) The transmitter and the receiver are now pulled up into air. The air is blowing with a speed 5 m/s in the direction opposite the river stream. Determine the frequency of the sound detected by the receiver.