Recent content by JBrandonS

What I love doing is listening to a audio lecture while looking at the book. You can almost always tell what it is he is writing down or pointing at while still getting the feeling of feynman being there.

Homework Statement This is question 1.1 from section 2-1 of New Foundations of Classical Mechanics: Establish the following "vector identities": (a\wedge b) \cdot (c \wedge d) = b\cdot ca \cdot d - b\cdot da \cdot c = b\cdot(c\wedge d)\cdot a Homework Equations The Attempt at...

I would also like to point out this this guide on how to become a good theoretical physicist, by a noble prize winner. It also provides links to free course work for everything so it should work great.

This helps clear it up. I was forgetting to modify the bounds and it was not obvious that the negative from the dx' = -dx would go away because you then have to flip the bounds. Thanks!

I am still failing to see where the x' goes when we combine them.

Can anyone explain how this substitution works and how you are able to use this to combine the two exp's. Still not seeing how that is possible.

I just want to point out one way of using this method to solve this problem since it seems to be non-obvious to some people. Write e^h as a series 1+ h + h^2/2 +... \lim_{h \rightarrow 0} \frac{e^x(e^h - 1)}{h} = \lim_{h \rightarrow 0} e^x \frac{ 1 + h + h^2/2+ ... - 1} {h} = \lim_{h...

Well, after vanhees71's explanation do you still believe this to be the case? And if so, under what conditions do you think this would be false or true? That is quite interesting. The main concern I have for that method is how can I handle the cases of a < 0 and a = 0, both of which provide...

Let me first say that I am self taught, I have only taken 1 semister's worth of calc classes but I have taught my self several courses. Getting on this site, however, makes me feel like I know so very little. So, thank you for your help but a lot of it I didn't understand. I will try and outline...

Initially it was brought in the notes of Feynman's numerical methods class that ##\int_0^\infty cos(b x) dx = \pi \delta(b)## I was unable to locate the original link I used to download the file so I uploaded it here. That equality is first given on page 16 of the pdf (labeled as page 14 in the...

Well, the dirac delta function is defined as ## \delta(a) = 1/\pi \int_0^\infty cos(a x) dx ## So you use that to say that ## \int_0^\infty cos(a x) dx = \pi \delta(a) ## and as you said this turns it into a piecewise function with a <0, a = 0, and a >0. Having talked to some other people it...

Homework Statement ##\int_0^\infty \frac{a}{a^2+x^2} dx## Homework Equations All the basic integration techniques. The Attempt at a Solution So, I saw this problem and wanted to try it using a different method then substitution, which can obviously solve it pretty easy. Since it is a very...

You rock, Never thought of that substitution. Thanks for all the help guys.

Could you elaborate a bit more? I understand what you are say I am just not seeing how it can be applied to this problem.

Thanks, I'll look into doing it that way. I have never used the Cauchy integral theorem so its going to take some time. Oh well, time to learn something new. :)