Idea Definition and 811 Threads

Hey guys. I have a lens problem: A lens has a power of 300 dipoters, and a radius a of 2 mm. An object is located just beyond the focal length to get high magnification. The space between the object is filled oil with an index of refraction 1.4. Estimate the resolution for 500 nm light...

A stuntman whose mass is 70 kg swings from the end of a 4.0-m-long rope along the arc of a vertical circle. Assuming he starts from rest when the rope is horizontal, find the tensions on the rope that are required to make him follow his circular path,(a) at the beginning of his motion, (b) at a...

I've had this idea for a while. I can't see anything wrong with it. Maybe someone here can tell me if it's unsound. The idea is based on the dimpling of a golf ball. To my knowledge the dimpling of a golf ball reduces air friction and let's it go farther. I even heard of someone dimpling a...

I've got an idea for a science project that I thought I'd run by you. I was walking home one day in the rain and I thought to myself, would I get more wet if I walk or run? At least initially I plan on ommiting wind... if I can get a handle on it then I'll add this to the mix. There are some...

In Goldbarz thread, CarlB voiced this idea: this is a possible response to Fermi's question "where are they" or to the apparent Silence. what's your reaction? BTW it is not as optimistic as it sounds right off because he just says "be able" and we might have the potential but fail to do...

how do i get to solve this integral,i have no idea whatsoever so no one should expect what i have done.it was presented to me by a colleague [x^(1/x)]^[x^(1/x)]^[x^(1/x)]^[x^(1/x)]^[x^(1/x)]^[x^(1/x)]^[x^(1/x)]...

Lets imagine that there is a gravitational field and you are in a position that if you fall a meter your g increases by 2m/s/s (I'm pretty that that's possible). In this case, the more you fall the more P energy you get and you get more K energy. In order for this not to contradict the...

I'm just curious to see what other people in this group have to say about this theory I have. I used to think that time was the fourth dimension. It seemed pretty logical due to the way dimensions are built up. The zero dimension is a point, the first dimension is an infinite number of...

What do you consider to be the basis or roots of your political philosophy and opinions? Is it Plato, the plight a certain group like the Palestinians, a cause such as environmentalism, national loyalty and basic patriotism, a greater concept or ideal such as world peace, an economic ideal, or a...

I'm having a bit of a hard time getting my head around this idea. Can anyone provide some links to good references, or offer an explanation here? Thanks.

If you are in the US, or have access to Public Broacasting Station signal, you may want to mark your calendar or your TIVO for Oct. 11 next week. http://www.pbs.org/wgbh/nova/einstein/ Zz.

define L[u] = a \frac{\partial^2u}{\partial t^2} + B \frac{\partial^2 u}{\partial x \partial t} + C \frac{\partial^2u}{\partial x^2} = 0 Show that if L[u] is hyperbolic and A is not zero, the transofrmation to moving coordinates x' = x- \frac{B}{2A} t t' =t takes L into a mutliple...

determine the inital velocity of a projectile that is luncked horizantaly and falls 1.5m while moving 16m horizantaly i tried everything all i figerd out is that they r displacmednts the accelaration is 9.8 and nothing i don't have enogh info to do anything please help me

surely building a craft to go to Mars without any infrastructure is pretty pointless & will end up being as beneficial as the moon. Wouldnt developing a petrol station in orbit be a better idea, and then a interplanetary ship that doesn't land but stays in space & a way to get up & down to it...

Hi all, New member here, found the forum when lurking around the 'net last night. A very brief disclaimer: I've a Chemistry degree, I work with computers in the IT security field, but I am NOT a Physics expert... far from that. I've read a lot of "popular" literature, and from my humble...

You can name more that 1 person and add more of your own. o:) 1)witty: 2)humorist: 3)kind: 4)cute: 5)helpful: 6)thoughtful: 7)wise: 8)hot: 9)cool: :cool: 10)strange: --------------------------------------------------- Threadholic: Mr Wolram, yomamma Gentleman: TSA, Astronuc

People tell me I should, I say why? I figure if my body doesn't tell me to eat then I won't (unless loss of appetite from illness or something). When I'm sleeping I hardly lose any energy, just my brain, stomach, and heart! I usually end up eating it more often than not, but I do NOT like...

I have this problem here. Let's say: A plumb bob does not hang exactly along a line directed to the center of the Earth's rotation. How much does the plumb bob deviate from a radial line at 40 degrees north latitude if we assume that the Earth is spherical?

I was thinking about creating a blog that would make regular posts about what a particular physicist does. The aim would be to provide a resource that would show how diverse the areas of physics study are, give details on what physics is being done and provide a little insight into what...

I don't know if this would work or not. What if you used one engine bay of an F-15 for a scramjet, the other for an SR-71 engine. That takes you to mach 10 and the edge of space. If you strapped PAM rockets to the missle racks on the wings and belly, could you make it to orbit velocity...

I would like to clarify that this idea that mass increases at relativistic speeds is an explanatory tool only (usually to explain why you cannot exceed the speed of light). It comes from the fact that in some equations, the factor gamma = 1/sqrt(1-v^2/c^2) multiplies the mass. However, I think...

This thread is an offshoot of https://www.physicsforums.com/showthread.php?t=83978&page=1&pp=20. Hmmmm, OK... ex·pand v. intr. 1. To become greater in size, volume, quantity, or scope: Air expands when heated. This critic's influence is expanding. 2. To speak or write at length or...

( 1 / 1 ) = ( B / A ) = ( A = B )

Well to begin I should say that I used to be a caffeine freak. I averaged 2L of Diet Dr Pepper everyday for the past four years. About three weeks ago I ran out of pop and, being extremely busy with college, I was unable to get to the grocery store for anything other than a few bags of food...

tempting idea, but crap? The universe is quantum mechanically. But no one understands quantum mechanics, as Feynman put it. On the one hand the pivotal role and accuracy of QM in describing nature. On the other hand the inability to interpret QM (1. quantum reality- what is a superposed state...

Sometimes on PF people use words and phrases that CAN seem aggresive without smiley faces or similar to 'disarm' them. However, as an alternative, we could use 'different' punctuation' to really be aggresive, without anyone knowing actually knowing, so also avoiding upset! Here, take a...

Consider some hypothetical universal rule which everything (including nothing) must satisfy. Then take that some hypothetical object that does not satisfy this axiom. What can be said about that object? Certainly it can not be said that it doesn't exist.

I have no idea what the hint tells me to do...please help me set the problem up...

In following up one of my idiot ideas that usually turnout to be absolotley stupid, I may have discovered, or rediscovered, an actuall result that I think might be worth publishing in arxiv. Since I am only a undergraduate student I am wondering what I should do. Should I talk to a doctor at my...

Don't know what forum to put this in. In what must be the most retarded step I know, we have been told to hand in a report in a "decorative container" worth a mind bogglingly large percentage of the mark. Considering my report is on the anthropic principle and its relation to cosmology...

First I called it an idea, not a theory. One might call it an hypothesis, though I do not think it is at that stage. I have posted it so someone who works on demminsions can help see it, maybe test it. To start off with, the string theory says that there must be 11 deminsions. I know this...

If anyone has been following that girl who was murdered in Florida... well the guy who confessed to the killing was... yes, a registered sex offender on parole. My father has always thought that the parole system in this country is the most disgusting thing imaginable. Someone my aunt know is...

Prove that there are no positive integers x & y such that \frac{1}{x^2} + \frac{1}{xy} + \frac{1}{y^2} = 1 . I really have no idea where to start. I tried rearranging the equation, but I could not see anything useful in any of the rearrangements.

Aaron Bergman has just called attention on science.strings to the new paper hep-th/0503249 which discusses the new idea of "split supersymetry". From the abstract: I don't know if this messes up current plans at Fermilab and CERN for hunting the Higgs. but it does look like it could give...

We are currently studying special relativity and using the idea of four vectors. The position 4-vector has been defined in class as \vec{X} = (ct, \vec{r}) \ \ \ \ \ \ \ where \ \vec{r} = (x, y, z) \ \ (ie: the usual 3 space position vector) and the velocity 4-vector is then...

I don't understand half of what is being said here but that's ok with me. When i understand something it is only because I've read Stephen Hawkin's A Brief History of Time (I acutally understood soemthings in the beginning and in the end) . I'm just wondering if anyone knows i a place i can get...

Hello. Our instructor gave us 2 sets of problems. Deadline is on monday. If anyone can share his / her idea, I would really appreciate it. Here are the problems: 1. Two positive point charges q and q2 are moving relative to an observer at point P; P measures the forces on the charges...

So this problem asks you to determine the magnitudes and irections of the currents in the resistors. I definitely understand how to determine directions, using Kirchhoff's Rules. But here is where I get stuck: the batteries have emfs of E1 = 9.0 V and E2 = 12.0 V and the resistors have vlaues...

Ok so I was sitting by my computer, and I suddenly thought "um this image I am seeing when I look at the monitor, or the sounds of cars I hear outside, where are they in the physical world exactly?" To better explain, let's think about it logically.. What components are part of creating this...

I have a general idea of what Maxwell did with electromagnitism, but I'm writing an essay for an Electronics class and need some information on how he directly or indirectly affected affected this topic.

I don't think anyone in class understands it, we went over it so quick. The only thing I seem to get is that uv - (integral) vdu = (integral) udv. You are supposed to assign u, v, dv and du, but how do you know which is u and which is v? What is the difference between du and dv? Are you...

ok... We were given the following question... (I apologize for it's length... please bear with me) A thin long cylindrical rod (mass M radius R and length l) is initially rotating about its long axis with angular momentum L. There are no external forces or torques however interestingly Ke is...

I've never understood most of the English movies. Matrix lies in the top ten(The Sixth Sense leads it) of my ununderstandable movies. Can anyone explain to me the theme and story and idea of the Matrix movies?

Hi, I'm doing a project when I drop a tennis ball and a basketball at the same time they hit the floor and try to show conservation of momentum after the seperate. of course the V(initial) would be the same before the objects hit the ground and after they hit, the Tennis ball would receive the...

If say, there is a false premise 'x'. Am i capable, psychologically, of convincing myself that this false premise 'x' is true? Therefore, can i cause myself to reach the point at which false premise 'x' becomes a true premise only in my private world? Is there a name for this?

Pipeline To Space? A carbon nano tube pipeline from the Equator to geo. orbit could pump massive amounts of H2 and O2 to space to be stored as rocket fuel. The pipeline would only have to be 1/4 inch diameter. http://www.newmars.com/cgi-bin/ikon...;f=5;t=198;st=0

http://www.cbsnews.com/stories/2004/05/11/60minutes/rooney/main616858.shtml I was watching this yesterday on 60 mintues and thought... wow that seems like finally a smart thing to do. I had thought of something very similar to it at one time, just never elaborated it to the point of the...

Potential Difference Problem..Help! :smile: Problem: Two parallel plates having equal but opposite charges are separated by 12mm. Each plate has a surface charge density of 36.0 nC/m2. A proton is released from rest at the point near the positive plate. Determine: The potential difference...

“Holographic” projector? Any idea how it works? I saw this a couple of years ago. It’s a projector that’s able to display 2D images or simulated 3D video into the air. Here’s the manufacturer’s site: http://www.io2technology.com/ The site has a few really neat videos. Any idea how this is done?

Ok I have this idea and i need you all to bash it so i can see what's wrong with it. Ok imagine a very very large black hole at distances like 10 billion light years, imagine that there could be black holes larger than we can fathom and imagine how many stars would lie behind such an anomaly...