Recent content by pastro

Perform dimensional analysis and you'll see you're still missing something. Should be: 2.36g = GMJ/r2 So you need to know the mass of Jupiter, which is the unknown quantity I referred to before. ω is the angular velocity, not the linear velocity. In this case, you can think of angular...

I'll take a crack (haha!) at this, although I ought to point out I'm not an expert in breaking concrete (although I've broken plenty of other things in the lab!), so don't stake anything important on this elementary guess. First imagine the slab doesn't break: Upon hammer impact, a small...

This is sort of a two step problem. Step 1.) Look at the first relevant equation (which appears to have a typo of one too many masses, but anyway...) The right side of that equation has Jupiter's radius in it, which is the thing you want to solve for. Given that on Jupiter's surface the...

Hello, I was wondering: \frac{dQ}{dt} = \sigma A T^{4} for a perfect blackbody. Also Q = mc\DeltaT If I take the time derivative of the above equation, set it equal to the power emitted by a blackbody, and solve the resulting differential equation for temperature, does that give me the...

So, is the principle the following: "The strong force respects charge conjugation. Because of this, in any strong force interaction where the initial and final states are their own charge conjugate and where the final state particles differ predominately by charge (the mass difference between...

In the first edition of Griffiths' Introduction to Elementary Particles, p. 129, I read: "In strong interactions, charge conjugation invariance requires, for example, that the energy distribution of the charged pions in the reaction p + p_bar -> \pi^+ + \pi^- + \pi^0 should (on average) be...

Thanks, that seems to do the job!

Thanks, but what I am really looking for is the tick marks to be logarithmically spaced, the same way LogPlot[] produces tick marks, but as a parametric plot. Your solution does not produce logarithmically scaled tick marks, just the log of the plotted variables on a linear scale. After...

Hello, I have been trying to make a parametric plot with logarithmic axes in Mathematica, but have been unable to find an option to do this. Can someone tell me how to do this? My code is below, and for reference, EnergyScint[b] is the Bethe-Bloch equation for energy deposit for a fully...

Thanks for all the great responses. After reading you replies, I think the problem is that I was using the "knee" instead of the point where the curves get horizontal. Cheers!

I'm a physicist, so take this for what its worth, but I think the issue is that a small cable diameter means more resistance, which means more power lost in the cable, which means less power getting to the motor. Thinking this way, if you want to loose no more than a certain amount of power...

Hi, I have Ids vs Vds characteristic curves for a MOSFET at Vgs = 2V and Vgs = 2.5V in both the linear (ohmic) and saturated regions. I wanted to try to figure out the threshold voltage for the MOSFET from this information only. I had two ideas of how to do this, but they differ by a factor...

I suppose the author might have used the thickness of the galactic disk instead of the radius...that gets things about right...but the context where I read this number needs an upper limit, and using the thickness of the galactic disk gives a lower limit.

I was reading a text which gives (without derivation/reference) the effective grammage along the line of sight through the disk of the galaxy as about 10^-3 g/cm^2. Is this the proper order of magnitude for the accepted value? By my calculation, I claim the galaxy has 1 proton/cm^3 ~ 2 x...

Hi, I feel extremely stupid for having to have this explained to me, but I am really confused by it. I recently encounter a proof of the fact that the brightness (energy/(time x area x solid angle x frequency)) of a black body can only depend on its temperature, not the properties of the...