# Search results

1. ### LED Current Drawing Question

Hello, You've probably already seen sites about "LED throwies" which are little circuits made of An LED A small 3V watch battery A Magnet Some Tape The idea is that you make these and then stick them to different things and the glow and are pretty. Anyway, with that background...
2. ### Solve for x(t), I just keep seeing 0

1. Homework Statement \frac{dx}{dt} = \sqrt{2(\frac{E}{m}) -\omega^2 x^2} 2. Homework Equations \frac{dx}{dt} = v 3. The Attempt at a Solution I keep ending up with the statement x=0. \frac{dx}{dt}=\sqrt{2\frac{E}{m} -\omega^2 x^2} Then (dx/dt)^2 =2\frac{E}{m}...
3. ### Monopole Moment of a sphere of charge

1. Homework Statement I'm really bad at these type of problems. I'm supposed to find the monopole moment of this continuous charge distribution. its charge is \sigma = const*cos(\theta) 2. Homework Equations p = \int r'\rho(r')d\tau which then since we are doing a surface charge...
4. ### De Broglie wavelength of electron

1. Homework Statement Show that the de Broglie wavelength of an electron of kinetic energy E (eV) is \lambda = \frac{12.3*10^{-8}}{E^{1/2}} 2. Homework Equations \lambda = \frac{h}{p} E = \frac{p^2}{2m} 3. The Attempt at a Solution I've played around with substituting and things like...
5. ### What does | f(t) | mean?

Hello, I don't know if this is general math or not, but I know it is a simple question that I just don't get so I put it in this forum. I'm kinda rusty at this, but I came across an equation in a book on wavelets that uses the notation | f(t) | inside an integral and I"m not sure...
6. ### Not an actual hw problem, but it might as well be

1. Homework Statement Basically I bought a new 7200 rpm hard drive and I was curious about it since it is a 2.5 inch notebook hard drive. What I was wondering was how many g's were pulled at the edge of the disk while it spun at 7200 rpm 2. Homework Equations \frac{v^{2}}{r} I'm...
7. ### Simple NAND flip flop question

something has always bothered me about nand flip flops and their use in memory so I thought I would ask this here and get it cleared up. In a basic nand flip flop like the one found here: http://hyperphysics.phy-astr.gsu.edu/hbase/electronic/nandlatch.html#c1" I understand that there is a...
8. ### Random MOND theory / dark matter question(possibly really easy to answer)

So I was googling around and I happen to see several references to MOND theory, Modified Newtonian Dynamics. Anyway, it proposes that there is this other new constant a_{0} that is a very very very low acceleration that exists. Basically, as far as I can tell so far the whole idea is that...