Recent content by johnwalton84

Thanks for your help.

Ok, that's helpful, thanks. I assume \Omega_{H}dJ represents work done. Does that mean the two forms dM = \frac{K dA}{8\pi} + work dE = T dS + work could be equated? dE - T dS = dM - \frac{K dA}{8\pi}

Hi, I'm looking for some help on where to start with this question: The surface area of a Schwarzschild black hole is A=16 \pi R^2_c where R_c is the distance of the event horizon from the centre of the black hole. Show that for such a hole containing quantized matter, its entropy can be...

Having said that, there's another part to that same question that I'm not sure of. It says A flint glass lens is placed in contact with the crown glass lens. The refractive index of the flint glass is 1.632 for blue light and 1.615 for red light. What is the focal length of the flint glass...

I see, thanks :cool:

I'm working through some questions on lenses, and I'm a bit stuck on this one involving radius of curvature. The part of the question I'm having difficulty with is The lens is made of crown glass of refractive index n=1.51. The radii of both surfaces is the same. What is the radius of...

Obviously not cos its worked :smile: Thanks for that imabug!

Would that not only work for i=100 though? If i is 200 then the mod(200,100) wouldn't be 0 so it wouldn't print?

I've written a program in Fortran which has a do loop of the form do i=0,20000 (operations) end do I want the program to print the values of the do loop, but only want it to print every 100th value of i (i.e. 100,200,300,400...20000), can anyone suggest a way to do this?

Thanks, I guess I was expecting the problem to be harder than that :rolleyes: . Yeah, the second part of the question involves evaluation by the Runge-Kutta method. :smile:

I'm stuck as to where to start with this question: The position function x(t) in a certain nonlinear system is described by the second order ODE: < equation.gif > Transform this ODE into a pair of first order ODEs for x1=x and x2=dx/dt. (Note that x2 represents the velocity in this...

Yes, I've got it now. Thanks. :smile:

I'm have trouble trying to evaluate the volume integral (shown in question.gif). I've attempted integrating it a few different ways, either achieveing an answer of 3 or 5.75, and I'm not sure where I'm going wrong. (Some of what I've done is in attempted_solution.gif) Any comments...

:blushing: of course :blushing: :smile: thanks it works fine in polars as well

Yes, but when you do that the i value on the left disappears and you get 21 = x+iy which suggests that there is no imaginary part of the solution (?) I haven't tried writing both sides in polar form, i'll try that now