A boat is travelling 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 throught a rigid support. The wavelength of the sound emitted from the transmitter inside the water is 14.45 mm . Aassume that attenuation of sound in water and air is neglisible. (a) What will be the frequency delected by a receiver kept inside the river downstream ? (b) The transmitter and the reciver 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 delected by the reciver. (Temperature of the air and water = 20^(@) C , Density of river water = 10^(3) kg//m^(3) , Bulk modulus of the water = 2.088 xx10 ^(9) Pa , Gas constant, R= 8.31 J//mol - K , Mean molecular mass of air = 28.8xx 10 ^(-3) kg//mol , C_(p)//C_(V) for air = 1.4
Answers
Answered by
0
Here is your answer:
Explanation:
Speed of boatu = 10 m/s
Speed of river stream w = 2 m/s
Wavelength of sound wave inside water is 14.45mm. Speed of sound inside water is
v=√ B / d =√ {2.088×10^9 / 103^}
= √2.088 × 10^3 m/s = 1445 m/s
Frequency of wave inside water is
n = v / λ = 1445 / 14.45×10^−3 = 10^3Hz
In this case source and medium both are in motion
Apparent frequency is given by
n' = (v+w)n / (v+w)−u = (1445+2) / (1445+2)−10× 10^5
=1447 / 1437 × 10^5Hz = 1.00696×10^5Hz
Similar questions