Find the Speed and Direction of a Wave with Constants A, B, and C

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The discussion focuses on determining the speed and direction of a wave represented by the equation y(x,t)=Ae^{Bx^2+BC^2t^2-2BCxt}. The solution simplifies to y(x,t)=Ae^{B(x-Ct)^2}, indicating a wave speed of v=C in the positive x direction. Participants debate the necessity of an imaginary constant in the exponential for the solution to satisfy the wave equation. It is emphasized that without the imaginary constant, the wave representation may not be valid, as regular exponentials do not fulfill the wave equation's requirements. The conversation concludes with a consensus on the importance of including the imaginary constant for a proper wave solution.
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Homework Statement


What's the speed and direction of the following wave(A,B and C are constants)
y(x,t)=Ae^{Bx^2+BC^2t^2-2BCxt}


The Attempt at a Solution


y(x,t)=Ae^{B(x-Ct)^2}

from (x-Ct)

v=C in the +x direction
 
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Are you missing the imaginary constant in your exponential? If so, then you are correct. If not, you have a diverging or decaying exponential rather than a plane wave.
 
No,it's original question.There's no imaginary constant.
So my solution is true.Thanks for checking.
 
No, there has to be an imaginary constant. You need to have something of the form

Ae^{i(x-vt)}

Regular exponentials don't satisfy the wave equation. The wave equation says that two derivatives in time equal two derivatives in space divided by the velocity squared.
 
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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