Biphysics Homework: Wrong Answer of P2/P1=R1/R2?

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SUMMARY

The correct formula for the relationship between pressure and radius in fluid dynamics is given by the equation p2/p1 = (r1/r2)^2 for general cases, and p2/p1 = (r1/r2)^3 specifically for shock waves. The initial formula presented, p2/p1 = r1/r2, is incorrect. Understanding the implications of these formulas is crucial for accurate calculations in biphysics problems.

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This discussion is beneficial for physics students, engineers, and anyone involved in fluid dynamics or biphysics, particularly those working with pressure calculations and shock wave analysis.

iram
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Homework Statement
Introduction to Biophysics homework
Relevant Equations
A pistol shrimp creates short, strong pressure waves by clicking its enlarged claw, and uses these blasts to stun small fish. The click is measured to produce a pressure wave with an amplitude of 80 kPa at the distance of 4cm from the claw. An explosion can be considered to by potentially fatal for humans when the pressure amplitude is approximately 20 Psi. At what distance from the shrimp is the click of the claw fatal for a diver? What is the total power of the click?
Is it done by using the formula p2/p1= r1/r2? I got answer 2.3 cm but it comes out it is wrong. Why?
 
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What are the units? What are the unit conversion factors? Over-pressure drops off with what function of distance?
 
iram said:
the formula p2/p1= r1/r2?
That does not look right to me. I would have guessed ##\frac{p_2}{p_1}=(\frac{r_1}{r_2})^2##, but from what I read online it is even ##\frac{p_2}{p_1}=(\frac{r_1}{r_2})^3## for a shock wave.
 
Yes, I think I get it now. The formula really doesn't look correct. I believe the one you mentioned above is the right one to use. Thank you :)
 

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