Recent content by astropi

Thanks Bandersnatch, in retrospect that should have been pretty obvious!

Venus is in the news! I looked up this well-regarded paper by A. S. Konopliv, W. B. Banerdt, and W. L. Sjogren Venus Gravity: 180th Degree and Order Model They list values for GM (see attached picture), such as GM 324858.63 ± 0.01 so in principle calculating M should be trivial. The problem...

I know the electric field is external. So perhaps another way of wording the question is: <v_o> = 0 in the presence of an E-field? I don't believe that is true. That is why we say in the absence of an electric field the velocity of a charged particle is random and thus on average = 0. However...

Ah yes, of course, <v_o> = 0 Thanks for pointing that out. However, I think my question still holds: in the absence of an electric field the velocity of a charged particle is random and thus <v_o> = 0. However, to derive the acceleration you have to assume an electric field since F = qE. How do...

Homework Statement First off, this is NOT a homework problem. This is a conceptual question I have regarding the derivation of the drift velocity v_d =[(qE)/m] \tau Typically, when this formula is derived, you first calculate the acceleration of a particle in the electric field (qE/m) and...

Yes, I know that, thank you. However, that is not my question. My question is: why does the range equation not give you the correct value for theta?

I figured it would work, and am uncertain why it does not, or where I made an error. For example, consider the following: R = 35 m, t = 3.2s, y_o = 1.4 m, v_o = 19 m/s with v_y = 16 and v_x = 11, therefore theta = 55 degrees (by the way these values are from an old exam). The range formula does...

Homework Statement First off, this is NOT a homework problem. I do not need an actual "answer", but I do have a conceptual question. Here it is: Consider a projectile motion problem such as a baseball being hit. Assume that it is hit and caught at the same height above the ground. In this...

Thanks for the response, but that's not what I'm looking for here. I have a few options I'm playing with, but I would still be interested in understanding the F-test if someone can explain how it can be applied to what I described above.

First off, this is NOT a homework question! That is, I'm not doing this for any course. So then, here's the question: I have some data points to which I fit a sinusoidal curve. I get the best (min) chi-square. Now, the question becomes how good a fit is my sinusoid? I was thinking that I...

Thanks! I really can't think of why I did not post the error in the first place, except that I've not had much sleep :) Edit: OK, got it! Thanks everyone for the help!

Thanks for the help, but unfortunately it did not work. I still get this error from Matlab: Error using fprintf Invalid file identifier. Use fopen to generate a valid file identifier. when I try my code: fileID = fopen('x.txt'); fprintf('%d\n',x); fclose(fileID); the error I...

I have output (stored in variable "x") that I want saved into a simple text file. If I use the command: fprintf('%d\n',x); it prints the data in a nice column. This is what I want. Then to save it to a file I try this: fileID = fopen('x.txt'); fprintf('%d\n',x); fclose(fileID)...

Thanks, I did not go through the entire 133-page document :) However, if you can recall where (page number) it says that the plasma temperature is around 20,000 K I would be interested in looking up the reference. What you said entirely makes sense, and I would like to read up on the physics...

Understood, but nonetheless, my original question was about the temperature of the gas :)