Recent content by jamdr

Can I replace Q with this: Q=\sigma 4\pi R^{2} That would mean the electric field from the spherical shell is: E_{shell}= \frac{\sigma}{\epsilon_{0} } Although I'm still not sure about the direction part of if anything else I've done so far is correct.

I got the equation for the spherical shell from my textbook, which uses it as an example. It says this about it: Electric field due to a uniformly charged spherical shell. Outside the shell, the field lines have spherical symmetry: they diverge from the origin. The field line pattern is the...

Homework Statement Ok, here's the problem. It deals with the superposition of electric fields from uniformly charged shapes: A uniformly charged infinite plane is located at z = 0, with a surface density of charge σ. A uniformly charged spherical shell with the same surface density is located...

Thanks for the help Dr. Transport. But in the end I ended up using this formula: f_n=\frac{1}{T}\int_0^T v(t) e^{-j n \omega t} dt where n is some arbitrary number of coefficients. Also, n is the index of f (an array). Then I plotted \overrightarrow{\left|f\right|}_n versus \frac{n}{T}...

Wait, what is a?

It's a math question I suppose. I need to know the steps to find a Fourier transformation. I know that MATLAB and other computer programs can solve this type of problem, but I want to understand the math behind it.

The signal is from a voltage supply. I see lots of pages on the internet about this, such as this one, which shows what the magnitude spectrum looks like for a square wave with an arbitrary number of co-efficients. But how would I actually create that graph myself?

I have this fluids problem I've been working on for a while, but I can't seem to get the correct answer. The problem is: A circular window with radius 25 cm in a submarine can withstand a maximum force of 1.23E6 N. If the interior of the submarine is maintained at a pressure of 1 atm...

I have these two fluids problems and I can't get either one (they are related). Can anyone point me in the right direction? 1. A 3.05 kg piece of wood (SG = 0.500)) floats on water. What minimum mass of copper, hung from it by a string, will cause it to sink? 2. A 3.25 kg piece of wood (SG...

I know I'm probably a few months late and I doubt you need the answer anymore, but I'll post this in case someone else comes across a similar problem. You were going in the wrong direction with your solution. This is not a conservation of momentum problem; it is a center a mass problem...

Correction Thanks, Doc. The correct answer is indeed 214 N. I meant that the method Halls used to solve it was correct, although I went through the calculations and plugged in the numbers myself. It is easier to use Newton's 2nd Law. I had tried this the first time, but arrived at the wrong...

That works Thanks for the reply. I think I follow your reasoning, although you did it differently than I did (I was trying to analyze the system only in terms of Newton's second law). The answer is correct, though. :smile:

I'm working on this rather simple pulley problem, and can't quite figure it out. It doesn't even involve acceleration. Could anyone help me out? Thanks. Here's the problem: A crate is pulled up using frictionless pulleys in the manner shown in the figure. The angle is 45 degrees. The masses...