Physics

Having some difficulty with a subatomic problem concerning K-alpha lines: "Light from the K-alpha line of an unknown material X is compared with the K-alpha line of Carbon. The wavelength ratio is lambda(x)/lambda© = 0.148. What is the matieral X?" I've got no idea where to go with this one. The only time i've used K-alpha lines is in regards to changes of energy levels. I know E=hf=hc/lamba, but i don't see how that helps

Why doesn't the moon fall on earth? What causes an orbit?

if an electron was released from rest from the negative plate, what is its speed right before it strikes the positive plate? How to solve it ? Does anyone know a formula to solve it ?

I was doing an experiment with some parallel plates and was wondering how much work is done by the uniform electric field by moving an electron from the negative plate to the positive plate of two parallel plates. How would you solve this???

I am in my final semester, I am doing project on OES that our school recieved. Basically I have to calibrate it for copper based alloys. I understand how it works, but since it's a project and deals with optics, I was wondering what fields/subjects involved are there. I hope to go beyond what is required and really bring out the interest aspects of it for my report and presentation, therefore I'd need to get some of the theory down, but I don't know where to start looking besides what wikipedia reccomends.

Hey all, am having difficulty with this question: Calculate how many conduction electrons pass through a given area per second when a current of 1A flows. I've used these formulae: Current density, j = i/A (i=current, A=cross sectional area) Current desntiy, j = nevD (n=no of electrons per unit volume, e=charge on electron, vD=drift velocity) I've taken an element of volume of length vDt and cross-sect area, A. I've surmised then that the total number of electrons in that area will be N=nAvDt. All of those electrons will then cross a plane in 1 second, so i've equated j=i/A=nevD, and substituted n from the earlier (bold) equation - n=N/AvD. However, tha…

HEy there, I need some help. We have to build this thing for science competition and i have no idea at all how to do it. Can anyone help me please. Here is the link: http://www.mrmaloney.com/nssl/events/2006-2007/0607_5-feb-yoyo.pdf

I don't really know where to post this, but its physics, I have a problem, recently I have been taking part in a scientific project, the project consists in the construction of a one stage coil gun, the idea and principle are simple, we have used capacitors to store the energy and then release it all in one go in order for the concept to work. So we have souldered 20 capacitors in parallel onto two long copper wires, we then charge the capacitors (2200 uf 50v electrolytic) and release the charged energy into a coil, the magnetic feild created for an instant pulls the projectile through the coil and launches it, up to here no actual problem..... now once done t…

i have a question... maybe im just crazy, and i have no basis for this quesiton. i have no idea. 8 different physics teachers i have emailed. and nobody believes that i can be right, or they have never answered back: In science, a vacuum is hated by nature. A true vacuum is perfect nothing. Why we're able to talk about true vacuums if they aren't actually anything is a good philosophy question to bring up next time you're at a party. Scientists have decided that it is impossible to create a true vacuum. First, we can't seem to get rid of every single atom from a jar no matter how hard we try. The fact that energy and mass are equivalent doesn't help. Energy can st…

I can't find my answer elsewere in internet. What will happen when photon passing through highly positive or negatively charged field or high voltage medium? I remember I seen it somewhere.

Im making a propane cannon (like a potato gun, but i will shoot anything that fits) and ive already built the barrel and fuel intake and air mix blah blah blah parts. So i was going use a simple piezo igniter from a barbeque to light this but it seems that is very inadequate and troublesome. I cant seem to lihgt my mixture of gas with this! I miniturized the thing (meaning i put propane in a 1 inch Cu pipe and sealed one end with a hole for the ignitor wires) and even thouygh its spars inside it seldom is successful in ignition. I weant something relieable. Im thining if i can make maybe a 12 kilovolt PSU i could just use a solid arc for an ignitor and that would be a sur…

I need help answering this question: A chage +q is located at the origin, while an identical charge is located on the x-axis at x= +0.50m. A third charge of +2q is located on the x-axis at such a place that the net electrostatic force on the charge at the origin doubles, its direction remaining unchanged. Where should the third charge be located? I need some pointers on how to answer the question. PLEASE HELP!

Hello, I am wondering if anyone has heard of anything that can be used as a heating element , yet is transparent. Like transparent metal for example ? Glass as we all know is a poor conductor of heat ! But there has to be something else Thanks

Does anyone know how to build a yo-yo that takes the longest time to descend a diastance of about 10 meters?

I assume you all have heard and probabbly read about the LHC project that is being developed in CERN ( European laboratory for particle physics ). Could someone explain to me how it works and what questions will it answer thus it's being considered as the biggest experiment of the year 2007. P.S. Thanks in advance

http://news.bbc.co.uk/1/hi/technology/6129460.stm Sound Likely? or not?

This is a weird thought I recently had: There is a digital version of things we see, smell and hear so far (perhaps more than I'm aware of at the moment). It goes to rationalize that all human senses will have digital counterparts. The question is, could this "digital revolution" pass on to other areas of our understanding, such as movement or transportation? Man, I do hate traffic. -F

One day I was thinking and I suddenly asked myself this question. If our brain temperature is 37 degrees Celsius, why do we feel uncomfortable (hot) when it's the same outside.

Sorry if this has been posted already, but I found it fascinating as I respect both of these indivudals greatly: http://www.npr.org/templates/story/story.php?storyId=5670911

As if I could make title of this thread more daunting enough, the length of this post should scare off 90% of you I've buried two questions in this post, which I've highlighted bold to make easier to see. I dont know why I've been thinking about it recently, but I was wondering about (Newtonian) gravity and the equations to calculate the movement of objects. I have a naive idea of how to do it: - For every object in space, sum up all of the gravitational vector forces acting on it, "press" the force against your object to plot its new coordinates. Basically, that does work, but its not very efficient. If you were trying to create a computer model of gravit…

One question, why does the normal force of a car on a banked road is actually greater than the downwards mg newtons of the car? shouldn't the normal force be simply a reaction force to one of the components of the weight of the car? please help~~~thanks

all right, so first of all, if you're reading this thread, thank-you, you're really cool, and even better if you can help... ok, so let's say we got ourselves a turbocharger thing, such as the one in the picture here: http://en.wikipedia.org/wiki/Turbocharger I wanna (really bad) know the efficiency of one of these (doesn't have to be the same type as the wikipedia picture one). You can think of it this way: You put 100KW of energy into compressing air. You pipe the air to the inlet part of the turbocharger, so that it works... compressing air into another tank. Given that everything in the system (except the turbo itself) is ideally (100%) efficient, (s…

Hi sup guys i need you help... What are the relationships between the gravitational potential energy of a suspended mass and elastic potential energy in a stretched spring? the answer to this... The gravitational potential energy of a suspended mass is inversely proportional to the elastic potential energy in a stretched spring is this answer correct... thanks in advance

Hello, I didn't know where to put this (since it's not really fitting anywhere else), but I am kind of learning variational calculus and more specifically Classical Field Theory (Hamiltonian mechanics and the like) and I need a good book (or even a explanation) that explains second class constraints really well. I am familiar with Lagrangian and Hamiltonian mechanics, but I am a little rusty on the Poisson bracket (especially when using vectors with indices!). The reason I ask is because I was talking about a field theory (I can't remember it now, it was just a toy model) with my professor in his office hours, and he goes to the chalk board and says "Well, bing b…

Why does a rocket fly when water and pressure from a pump is added??? I know this is probably very easy, but I'm not good at science and I'm new to this forum so I don't know how things works yet.