Schrodinger and Infinite Square Well hell

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The discussion focuses on demonstrating that the Schrödinger equation \(\frac{d^{2}\psi(x)}{dx^{2}} + k^{2}\psi(x) = 0\) has the solution \(\psi(x) = A\sin(kx)\). Participants emphasize that the solution can be verified by substituting \(\psi(x)\) back into the differential equation. It is noted that understanding general solutions is crucial for solving such equations. The original poster seeks guidance on how to prove this solution rather than just accepting it as a fact. Ultimately, the discussion highlights the importance of substitution in confirming the validity of solutions to differential equations.
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Schrodinger and Infinite Square Well... hell

Homework Statement


Show that Schrodinger Equation: \frac{d^{2}\psi(x)}{dx^{2}}+k^{2}\psi(x)=0 has the solution \psi(x)=A\sin(kx)

Homework Equations


k=\frac{\sqrt{2mE_{tot}-E_{pot}}}{\hbar}

The Attempt at a Solution


I already know that \frac{d^{2}\psi(x)}{dx^{2}}+k^{2}\psi(x)=0 is a differential equation and has a solution \psi(x)=A\sin(kx) but it's just something learned as fact. How do I go about showing it?

Any pointers would be appreciated... thanks in advance!
 
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Generally solving differential equations involves knowing general solutions such as the one you've shown. If you wanted to prove it you could just simply sub it into your differential equation and prove that it does indeed satisfy the equation. I.e differential psi twice and add it with (k^2)*psi
 


Thank you.. Just needed a kick in the right direction... Didn't even need to use the value of k.
 
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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