Recent content by MasterD

Muchos gracias.

Hi, I am looking for a graph or function that shows how much water the air can contain as a function of temperature (I think the warmer it is, the more water the air can contain, but I'd like to see an exact graph or function). Thanks! MD.

Thanks for your reply Tim. \rho is not constant, however.. D/Dt is indeed the convective time derivative.

Is this the right format of the energy equation (equation 2.10)? http://www-solar.mcs.st-and.ac.uk/~alan/sun_course/Chapter2/node3.html#energy \frac{\rho^\gamma}{\gamma-1}\frac{D}{Dt}\left(\frac{p}{\rho^\gamma}\right)=-L I know it in a different format: \frac{dp}{dt}+\gamma...

Ok; thanks a lot; I will look further into this. One more question: Shouldn't there be any scaling WITHIN the exterior derivative? Something like: (dv)_{ij}=\frac{1}{h_1}\partial_i h_1 v_j - \frac{1}{h_2}\partial_j h_2 v_i ?

Hi, I have a certain NON-orthogonal curvilinear coordinate system in 3D (in the metric only g_{13}=g_{23}=g_{31}=g_{32}=0) and I want to take the curl (\nabla\times\mathbf{v}) of a vector. Any idea on how to do this? The only information I can find is about taking the curl of a vector in...

Hi, I am looking for a certain operation that makes a 1 tensor from a 2 tensor by filtering out only the diagonal elements. For instance, (f1g1 f1g2 f1g3) (f2g1 f2g2 f2g3) (f3g1 f3g2 f3g3) becomes (f1g1) (f2g2) (f3g3) after a certain...

In my book it states that if you shine a laser beam on a black hole some of the light is backscattered; so that way you can detect black holes; why is that? Is it because of diffraction or is it because of quantum mechanical effects?

I am struggling with an understanding on what the longest proper time an observer can spend before he will be destroyed into the singularity. How should I approach this problem?

Thanks guys. I got the answer. You should contract over the first index; so $(\nabla\cdot\mathbf{A})_{jk}=\frac{d}{dx_i}A{ijk}$

I want to calculate the divergence of a two dimensional 3 order tensor; e.g. nabla=(d/dx, d/dy) and Ax = ( C D) ( E F), Ay = ( G H) ( I J) (it's a 2x2x2 cube). Index notation: (nabla)_i = d/dx_i and elements of A are A_ijk How do I contract it properly...