Mystery Definition and 897 Threads

I'm currently going through some questions and came across quadratic and linear simultaneous equations. Solve the equation: x + y = 1 x^2 + y^2 = 16 I am not interested in the question itself but rather the explanation the book gives me which says after...

I just read that the mystery of the "missing solar Neutrinos" has been solved. That is, the "missing" stuff is converted to Muon & Tau Neutrinos (which have been detected at the SNO). I'm confused ... If Solar Neutrinos are very "non-interactive", then how do enough of them get converted...

I was wondering, if dark matter (DM) halos are spherical in nature and increase in density as a function of distance from the galactic core, why does the density drop off so suddenly and why would stars on the edge of a galaxy feel an inward pull? To elaborate on the 2nd question, if DM...

I thought optical phonons only existed in crystals with two or more types of atoms in a unit cell. But I keep reading references of optical phonons in single atom crystals, like silicon. What's the deal here?

So black holes are incredibly dense points of matter that affect everything in their area with very powerful gravity field, including light. \ So, asuming that gravity affects only matter, that by default says that light is a physical particle. So why don't the regular laws apply to it...

Hi, I've been learning about transistors lately through the Horowitz & Hill book. I'm surprised to see that when used as a current source the collector voltage only changes with load voltage with an ideal transistor. When I say I'm surprised I mean that in non-ideal models the base current...

Simultaneity Let's imagine there is a train moving at the speed of light. When in the middle, two lightning flashes appear on it's left and right. Why is it that it sees the right flash before the left? And if it is moving left to right, why does it see the left before the right? It is to...

I found a powder in my driveway earlier today. I have no idea where it could have come from but I'm curious because it seems so out of place. It's very dark brown, almost, but not quite black (see attached) and utterly uniform in colour. It's extremely fine, finer than icing sugar. So fine...

Hey Chem geniuses! I am a struggling high school chem student who couldn't combine water with water without blowing something up so some help would definitley be appreciated. My chem final has been issued already and it is as follows: Put 5 mL of 3 M aluminum chloride solution in each...

http://www.collegehumor.com/video:1755006 This may be old but... How does this work? They need to have a huge warmth transfer coefficient for this to happen? Maybe the water is at 0°C already and a small amount of energy should be taken to get this effect. Is it electromagnetical or is the...

I just read the following fact and it somewhat defies my usual logic. \lim_{x\to\infty} \sqrt{x^2+x} - x =\frac{1}{2}. Now my usual logic tells me that as x becomes large, the leading term in a polynomial sequence is the major one and therefore the x^2+x becomes x^2 so \sqrt{x^2+x} becomes...

So I learned today that Bleen is the integer number between 6 and 7. You might be a little upset about this. However, bleen can still be useful to you, since it is also related to Grue[/color], a very convenient term not to distinguishing blue from green in language[/color]. The philosophical...

Say we have two waves of the same amplitude are about to collide with each other. The preceeding wave travels at a slightly higher speed before interacting with the final wave. However, instead of passing through the final wave its speed and size is transferred into the final wave where it...

I was staring at my calculus book when this came to me, so apologies if its a little murky. I've been thinking about Hubble time and noticing something odd, that my astronomy professor really couldn't (or wouldn't) answer. t(u)= 1/H x 10e12 years which didn't quite work because if the...

There are two magnets stuck together through magnetic force but there is a pane of glass seperating them, when I spin the magnet closest to me clockwise, both of the magnets spin and move to the right and down, when I spin them anti-clockwise, they spin and move to the left and down. The...

What causes the horizontal lines that move down a computer or TV screen when you video tape it?

We know that Truthers always tell the truth but Liars will always speak falsely. An island comprises entirely of Liars and Truthers.. Precisely 45 people attended a dinner in the island. Each one of them sat at a big round table. After the dinner was over, each of the attendees was...

How does a photon move.If it is a particle and moves in a straight line,what do we mean by its frequency in E=hf?

An evil king has n bottles of wine, and a spy has just poisoned one of them. Unfortunately, they do not know which one it is. The poison is very deadly; just one drop diluted even a billion to one will still kill. Even so, it takes a full month for the poison to take effect. Design a scheme...

1. do different people have different dreams? 2. how often does one dream? 3.what affects the dreams that one has? 4. why do we often forget the dreams we had?

[sorry if this has been asked before, but this is a question I've been asking people] Ok, now just about every one at one point has heard about a "ghost". And lately I have been thinking to myself that I have been seeing them around the house, because when i come out of a room, and i pass...

The color code for hidden text is #black. Some of these questions are insanely tough. I'll post the answers after sufficient participation. 1) The first is a picture of a person who starred in a famous American sitcom of the seventies. The second is of a famous director. The third is that of...

Wow, this forum seems to be full of engineering brilliance :P. Anyway can anyone help me with this. The stages in sand casting to produce: a) solid object that is thinner at the centre than at the ends b) hollow object with two openings of diameters less than the component diameter...

In fusor you react one deuterium with another one. So you should get [SIZE="1"]4He[SIZE="1"]2. Why does it ejects one proton or neutron from nucleus?

Two people sat eating fish and chips in the open air...both see a car shift sideways. There was no way for it to have done so and it did not make a sound as it moved. One minute it was there...the next it shifted a foot or so sideways. Both people stopped mid chip and looked at each other for...

It seems reasonable to start a thread about this. Please feel free to post any pertinent information. For starters, see the main page of NUFORC - The National UFO Reporting Center. http://www.nuforc.org/ This is the report database for Illinois. See November 7th, 2006...

I saw a bright green meteor yesterday. What would cause a meteor to be bright green? Is this common?

At work we have these magnetic blocks which have arms attached to them for dial indicators. They are use to hold the dial indicators like an extra pair of hands. They work great. My question is how do they work!? The magnetic block has a switch on it. This switch will turn the magnet on...

Homework Statement Why F=ma? And what is mass? Homework Equations The Attempt at a Solution

I just thought of something, imagine this scenario: You have an empty bottle of sode\water(whatever) and you hold it lopsided, at the point where it theoretically would stand still. But then move the top half a millimeter towards the center, and then release it. Then it will "fall" to the...

I found this to be an interesting article by Benjamin Radford on orb photography. Anyone have any photos with really unexplained effects? I tend to think that most "orb" photographs I've seen are so obviously dust or small insects. Who was the first to claim dust was actually "ghosts" Does...

Here I have an elusive schematic of a 20 dB amp at around 20 MHz. It works as a unity gain amp when the control line IFG2 is open. When grounded it amplifies by 20 dB. The diode is a pin diode and supposedly has 83 ohms when the current is flowing through it. The +10 volts comes from a...

I have found a quote I've been looking for. It's the lower one in my signature right now: "Science is everything we understand well enough to explain to a computer. Art is everything else." However I don't know just who said it. Most web sources say David Knuth, but some say Donald Knuth...

Today the professor wrote down the following for use in an integral: \frac{1}{2}cos(2\theta)=sin\theta cos\theta i am not sure is this is correct. i have tried to prove this and cannot, i have also not found it in an table of trig identities. Is this a valid identity? i am not sure since...

an electron moves within a uniform magnetic field of .2T at a speed of 5x10^5 m/s. What is the magnetic force on the electron? I used Fm=qvBSin and got 1.6x10^-14N but the answer is that it can't be determined with this info why not?

I do not know if this is the correct modern term, but it seems that particles can be thought of as wave packets? no matter what they are, what is manufacturing these packets in such a way that our universe is as we see it?

What IS this? Yesterday I was driving home from school when I saw that in the clouds there was what seemed to look like a portion of a rainbow :confused: :confused: I thought it was weird, so I took a picture of it while driving, with my cell phone, so it's not the best quality :redface...

Hey, I understand GR pretty well and I realize how and why light is constant and appears constant from any frame of reference. My question is that even though nothing can reach light speed except a photon (or massless particle), how would other photons appear to them? In other words, from a...

Ok so I mixed alum (aluminium potassium sulfate... I think), flower,and cornstarch in a 1:1:1 ratio, and put that in a covered pot and heated it till it produced no more smoke/fumes. This was an attempt to make a rapidly oxidizing powder in air. It was very blind science, I am sorry to say. It...

SkyBlue=WaterBlue? No! Hey guys, I always thought that water is blue because it reflects the color of the sky. Today when I was surfing through the web I found this webpage that says that water is blue because it really IS blue! Check it out...

faucet mystery (help!) I'm in a physics class and we have 3 sinks in the class room on the same wall.All the faucet are off. When you turn one faucet on all 3 faucet are on and the water is running from them. So; when you turn faucet 1 on , 2 and 3 are also on when you turn faucet 2 on , 1...

can anyone please help me with this. why is 0! = 1? :confused: thanks in advance to anyone who can help.

if a standing wave is a wave which transfers no energy, how is it that a guitar string produces a sound? because it produces it via a standing wave, and the sound is sound energy, so where does the energy come from?

I have this problem I just can't figure out. Current = A (Ampere) i(t)=z(e^t/(RC)) where z is the initial current at t=0, R is the resistance in Ohms and C is the capacitance expressed in secondary units as F (Farad) - Express the units of F in terms of seconds and ohms So, this...

I get the theory of special relativity, it is the logical conclusion drawn from the two facts that: a) the laws of physics are the same in all reference frames b) the speed of light is constant in all reference frames what I don't get is why einstein thought the speed of light was constant...

I understand why mechanical systems that are not capable of self repair wear out, but for years now I've been totally puzzled as to why things which do not have wearing parts wear out, such as - phosphores, rechargable batteries, capacitors, fluorecent lights, electrodes, vacuum tubes...

What's preventing Saturn's rings from condensing into a moon? Or Jupiter's, Uranus' and Neptune's for that matter?

a perfectly-circular pizza comes in a square box with a card in the box. the card measures 140mm by 70 mm. what is the diameter of the pizza? i tried similar squares but this did not work? any help anyone

I've just come across a problem and the equation within this problem isn't entirely explained in the text. I've searched on the net for this same 'lattice energy' equation, but there have been no results. Here is the equation: E = Aexp^ \frac{-r} { \alpha} - \frac{Me^2} {4 \pi \epsilon_0 r}...

Now this bugs me. First there were no negative numbers. Then there were no square roots to negative numbers. Then every real number had two square roots, but no word on imaginary numbers. Luckily for me, I had a calculator that told me the square root of i wasn't some other type of number or I...