- #1
bananabandana
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- 5
Homework Statement
Please see attachment for diagram. The two boats are coherent sources of sound waves (phase difference ## \phi##) - i.e it's a double slit problem.
Prove the formula given for ## y_{max}##.
Suppose the whale is 20m long. How large should the sonar frequency ##f## be so that the whale can always be detected? Assume ## B=2.18\times 10^{9} Pa ## and ## \rho =1.05 \times 10^{3} \ kg ##
Homework Equations
$$ y_{max} = \frac{d \lambda (n+\frac{\phi}{2\pi})}{a} $$
Where ## y_{max}## is the ##y## value at which the two sources constructively interfere for a given depth, ##d##. The depth of the whale (the tube shaped thing) is ## d=350m##.
The phase velocity of the sonar waves, ## v_{p}## is given by:
$$ v_{p}=\sqrt{\frac{B}{\rho}} $$
The Attempt at a Solution
Is it sensible just to substitute ##y_{max}=20## and just do the algebra? ( I have already done the proof for ##y_{max}##.)This would seem the obvious thing to do from the diagram ( and since the question is only a couple of marks). But I'm just wondering if this would really work. It says earlier in the question that the whale is moving horizontally - so I'm just thinking there might be a more complete way to approach the problem, but I don't know how to do it...