Recent content by krishna mohan

I had found this...I wanted the 3D Fourier transform...not the 2D one...

Hi.. What is the Fourier transform of 1/r? Is it proportional to 1/(k^2) ? How do you prove this?

I am a little confused here... Even if you move the balance to some other position, the potential energy is not going to change..as the increase in PE due to one mass moving up is compensated by the decrease due to the other moving down.. In a slightly tilted position, where does the...

Confused about a simple thing... For a common balance, since both arms have equal weight, what causes the pole to choose a horizontal position? Shouldnt it be stable in any other position as the torque around the centre is zero for any other position too?

I have to prove some general identities in GR...and not for a particular metric.. In GRtensor, can we put a metric to be arbitrary? Can we just set g_{ab}= g_{ab}(e,f,g,h) where e, f, g and h are arbitrary variables...and not give an explicit form?

Hi... I have just started using GRtensor... I realize that the calculations in GRtensor have to be done only after specifying a metric... Is there any package which can directly do symbolic manipulation without using the metric?

For some reason, am not able to edit this post. Please see the new post on the same topic.

Hi... I have been pondering over this problem for sometime... This is problem no 4-9 in Binney and Tremaine's Galactic Dynamics first edition... In a singular isothermal sphere with an isotropic dispersion tensor, the RMS speed is \sqrt{\frac{3}{2}}v_c, where v_c is the circular speed. In...

I just dug up this old thread on this issue... https://www.physicsforums.com/showthread.php?t=334697

Hi... It is an easy to see fact that, instead of moving along the hypotenuse of a right triangle, one starts from the lower corner and reach the upper corner moving only along the directions of the other two sides, i.e only vertically and horizontally and not diagonally...the distance moved...

Okay... But if a is not equal to b, then won't the symmetrised version have an unwanted factor of (1/2)? i.e if a=c and b=d, one would like to have 1 as the answer...but the symmetrised version would give 1/2...

Could someone tell me what would be the partial derivative... \frac{ d g_{ab} }{ d g_{cd}} ?? Such expressions occur when one does variations of gravitational action... Note: For some reason, the d needed for derivative is not appearing in the post...although it was visible in the preview...

Fairly straightforward question: Why are nanoparticles generally made using metal, that too generally using gold, silver etc?

Thanks! I have got the book...and it was very informative...

Yep..found that.. Actually I dug up your old post on the same issue where you have given the reference of the Bardeen paper... Thank you very much!