How to use Laplace's eqn to do this?

  • Thread starter neelakash
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In summary, the conversation discusses the calculation of gravitational field and potential at a point near an infinitely extended thin sheet of mass. The speaker has already calculated this using a direct method and is now wondering how to solve it using Laplace's equation. They suggest using the method of images and note that the potential must satisfy the equation for gravitation. However, they do not know the appropriate boundary conditions for solving the problem. Another speaker suggests using the analogy to Gauss's law, where mass density replaces charge density.
  • #1
neelakash
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Homework Statement



We are to calculate gravitational field and potential at a point near an infinitely extended thin sheet of mass by using Laplace's equation...

Homework Equations


The Attempt at a Solution



I have already calculated this directly,using fundamental formula.
Now I wonder how to use laplace's equation to solve this.Should we make an attempt like method of images?How else an be done?
 
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  • #2
For gravitation, the potential must satisfy the equation
\begin{equation}
\nabla^2 \phi = \frac{4\pi G}{c^2} \rho,
\end{equation}
where $\rho$ is the mass density, so outside the plate, the potential satisfy the Laplace equation.

But.., I don't know the well-posed boundary conditions you must apply in order to solve your problem. I'm sorry, is as far as I can help you. Keep trying.

Good luck.
 
  • #3
Hi --

hope this isn't too late.

But yes, this problem becomes most simple when you note the analogy to gauss's law the Gravitational laplace equation has. Except charge density has been replaced by mass density.
 

FAQ: How to use Laplace's eqn to do this?

How do I apply Laplace's equation to a specific problem?

To apply Laplace's equation to a specific problem, you first need to understand the problem and determine if it is a suitable candidate for using Laplace's equation. Then, you can use the equation to solve for the unknown variable(s) and apply any necessary boundary conditions.

What are the main steps involved in using Laplace's equation?

The main steps involved in using Laplace's equation are: identifying the problem, determining if Laplace's equation is appropriate, solving the equation using known techniques (e.g. separation of variables), and applying any necessary boundary conditions.

Can Laplace's equation be used to solve any type of problem?

No, Laplace's equation is a specific type of partial differential equation that is only applicable to certain types of problems. It is commonly used in electrostatics and fluid dynamics, but may not be suitable for other types of problems.

Are there any limitations to using Laplace's equation?

Yes, there are some limitations to using Laplace's equation. It assumes that the system is in equilibrium and that there are no time-dependent changes. It also has certain boundary conditions that must be met in order for the equation to be applicable.

What are some common techniques for solving Laplace's equation?

Some common techniques for solving Laplace's equation include separation of variables, Fourier series, and complex analysis. The specific technique used will depend on the problem and the boundary conditions given.

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