Wave constructive and/or destructive interference question

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The discussion revolves around a physics homework question regarding wave interference from two sources, A and B, creating water waves. The individual wave crests from both sources are 5 mm above the undisturbed water level. The participant initially suggests that the displacement at point "x" is -5 mm, assuming only one wave source's effect. Another contributor clarifies that if point "x" is at a crest from source A and a trough from source B, the total displacement would actually be 0 mm. The participant acknowledges this clarification and expresses gratitude for the assistance.
kirsten_2009
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Homework Statement


https://portal.utoronto.ca/courses/1/Fall-2014-PHY100H5-F-LEC0101/ppg/quiz%2061016132114/f1q2g1.jpg

The figure shows two sets of water waves, created by two sources labeled "A" and "B." The solid half-circles represent wave crests from A, and the dashed half-circles represent wave crests from B. Suppose that individual wave crests from either source A or source B alone are 5 mm above the level of the undisturbed water. Then the displacement of the water [above or below the level of the undisturbed water] at the point marked "x" [with the arrow pointing toward it] is

A.) -10 mm.
B.) 0 mm.
C.) +5 mm.
D.) +10 mm.
E.) -5 mm.

Homework Equations


[/B]
N/A

The Attempt at a Solution


I think it would be E.) -5mm because if we are just taking one wave set alone (either A or B) then there would be no interference from the other wave set and if the displacement from rest is 5mm then the opposite displacement must be equal in magnitude...? But I don't actually know...I'm just thinking it out...would you please correct me if I'm wrong? Thanks in advance!
 
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I cannot see your figure. Could you check to see that it was attached properly?
 
Although I cannot see the picture, here is a hint. You can add the wave effects together. So, if x lies on a wave crest from A, (+5mm), and the midpoint between crests from B (-5mm), then the total displacement at x would be 0.
 
Hello,

Yes, unfortunately there was no way to upload the image but thank you for your help...it actually helped me get the answer! :)
 
The book claims the answer is that all the magnitudes are the same because "the gravitational force on the penguin is the same". I'm having trouble understanding this. I thought the buoyant force was equal to the weight of the fluid displaced. Weight depends on mass which depends on density. Therefore, due to the differing densities the buoyant force will be different in each case? Is this incorrect?

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