Mystery — 395 discussions

  1. K

    Green transparent brittle material found in fire ash

    I came into my engineering class this morning and our teacher showed us this strange material. He got the material from a student who recently went hiking. According to the student, he and his father went into the woods and started a fire in an old metal tire rim. They threw a bunch of old...
  2. A

    Why does a Tippe top flip to spin on its stem?

    Homework Statement Why when a Tippe top is spun with high angular velocity, it spins until it lifts its body of the top off the ground with its stem pointing downward? Homework Equations The Attempt at a Solution The only reason I could think of was that it's kinetic energy is...
  3. S

    What should I write in a theory review for my investigation?

    I have to finish my investigation and the outline has something called a Theory review. It defines it as: a story that generates interest in the reader for the field of your research and link to practical investigation to follow.:confused: Now this maybe very simple but I'm not sure what kind...
  4. J

    Undergrad How would you define time?

    I recently realized that we use this concept constantly but I have absolutely no idea how I would answer this. Never in any school physics lesson or university lecture I've attended has anyone even mentioned this. It's just sort of taken for granted because we all have experience of it passing...
  5. S

    Graduate What is the 'faint regime' in cosmological explosions?

    What do they mean with "faint regime", when they talk about cosmological explosions?? (e.g X-ray flashes) thnx
  6. C

    What Causes Jetstream Damage on Boat Hulls?

    Hello. I'm new to the forum, and a non-expert trying to learn about topics for a mystery I'm writing. Hope someone can tell me if this is plausible: Drilling equipment on the seafloor either malfunctions or is sabotaged in a way that shoots a stream of water mixed with seafloor sand upward...
  7. B

    Why do we use probability amplitudes in quantum mechanics?

    Homework Statement What physical phenomenon requires us to work with probability amplitudes rather than just with probabilities, as in other fields of endeavour? Homework Equations The Attempt at a Solution Not sure. The wording of the q throws me... phenomenon i.e...
  8. D

    Why doesn't a hydrogen gas ionize in an electric field by tunneling?

    Here comes a pretty hard question, which not even my QM teacher has been able to answer. When we think about one hydrogen atom, and put it in an electric field along the z-axis \bar E = \bar e_z E. Then the potential for a hydrogen atom will look like this: U = -\frac{e^2}{4\pi \epsilon_0...
  9. Ivan Seeking

    Mystery Missile Launch in California

    http://www.theglobeandmail.com/news/world/americas/pentagon-stumped-by-apparent-missile-launch-off-us-coast/article1791785/ https://www.youtube.com/watch?v=CeXNC8k9FKU
  10. W

    Undergrad Why does wind damage scale with the cube of velocity?

    Hi Guys, I understand that the energy associated with wind damage from a hurricane goes as the third power of the velocity of the wind. How is this relationship derived? I ask because when I think of wind energy, I think of Kinetic Energy going as the square of the velocity...
  11. nomadreid

    Graduate What Does the 1 in the Spacetime Equation Mean?

    In my reading I came across the equation ds2 = −dt2 + 2t/r dtdr + (1 − (t/r)2)dr2 + (BKr)2(dθ2 + sin2 θdϕ2) where s is spacetime, t is time, r is radius and the others are not important for my question. What I do not get is the "1" in the (1 − (t/r)2)dr2, or dr2− ((t/r)2)dr2 . This seems...
  12. H

    Why does a secondary rainbow form with reversed colors?

    Homework Statement What causes the faint rainbow outside of the primary one, and why are its colors reversed? Homework Equations I know that rainbows form from passing through raindrops but I don't know about the second one. The Attempt at a Solution
  13. Z

    Two beads sliding down a frictionless hoop: when does it lift off?

    Homework Statement Two beads of mass m are initially at rest at the top of a frictionless hoop of mass M and radius R, which stands vertically on the ground. The beads are given tiny kicks, and they slide down the hoop, one to the rigth and one to the left. What is the largest value of m/M...
  14. H

    Grounding one speaker coil wire instead of both

    I have uploaded the pic of schematic of two type speaker. The left side of pic shows the usual one speaker where sighnals are fed at both the wire of the coil. 1) I assume the right side of the pic(speaker)(which I imagine) should work , where I have grounded one of the coil and ths signal is...
  15. I

    Why does work by conservative forces equal zero when potential energy doesn't change?

    Homework Statement Work done by conservative forces = -\DeltaU Homework Equations Above. The Attempt at a Solution Here is the whole equation: Wc+ Wnc = \DeltaK. Wnc = \DeltaK + \DeltaU. So, Wc = -\DeltaU. But, for example, how does that apply in a situation with no...
  16. 2

    Undergrad Do wormholes exist and can they be created?

    wormholes...a mystery or not! do wormholes actually exists? if yes, then, is it true that they act as shortcuts for some other destinations in the universe? and lastly can man himself create them!?.....all a mystery 4 me!
  17. W

    Graduate The Mystery of Why Photons Have No Mass

    Why doesn't the Higgs field give photons mass?
  18. Ivan Seeking

    Is a Virus and Bacteria Combo Causing Bee Colony Collapse?

    http://wjz.com/local/honey.bees.2.1953775.html
  19. Ƒ

    What does it mean to be smart?

    What, in your opinion, exactly is smart? Is it looking at someone and seeing something no one else does? Is it finding a new way to do something? Or is it by being the cleverest?
  20. C

    What does a transistor do and how do its terminals work?

    Homework Statement The base-emitter voltage, V_be, typically never exceeds .6V. Because of this low value, the base-emitter junction must be protected against too high a reverse voltage. A diode is usually used to protect the junction as shown in the figure for a npn transistor. a. Explain...
  21. J

    Graduate Is the Higgs Boson Misunderstood Due to Misleading Analogies?

    http://www.higgs-boson.org/ Is it as garbage as it looks?
  22. F

    Graduate What Is the Mechanism Behind Dark Flow?

    How does dark flow work? Thanks
  23. K

    Why do HCl and CH3COOH require the same NaOH for neutralisation?

    Homework Statement 25 cm3 of 1 mol/dm3 ethanoic acid requires a smaller amount of sodium hydroxide for complete neutralisation than 25 cm3 of 1 mol/dm3 hydrochloric acid. True or False? 2. The attempt at a solution I selected true, but I was wrong. Both of them require the same amount...
  24. D

    How can you test if a crown is pure gold without damaging it?

    Homework Statement Once upon a time the famous archimedes was given a problem to determine if a crown supposedly made of pure gold actually contained some silver. If Archimedes was your lab partner, explain how the two of you could quickly determine if the crown were gold or not without...
  25. P

    Undergrad Is there a formula to predict or generate prime numbers?

    Is there any mathematical formula to predict / generate / or test the prime number??
  26. G

    What brain signals control writing a word?

    how many types of brain signals are there? or if a person thinks of writing a word the signals that perform this action what are those called..? (brain signals is not my subject but i want this knowledge to further use it in a signals and systems project relating to human brain) thnx
  27. B

    Graduate How can we see galaxies receding faster than light?

    If galaxies aer expanding fast than the speed of light how are we able to see them. At the moment this expansion surpassed the speed of light shouldn't these galaxies disappear or remain unchanged visually?
  28. K

    What does O represent in the virial expansion F = F0 + kBT log c + ½ cb1 + O(c²)?

    Please, This equation is based on the free energy of perfect gaz : F = F0 + kBT log c + ½ cb1 + O (c2) ½ cb1 is the excluded volume term (c is the concentration) but what is O ?
  29. G

    Depth of a jam tin submerged open-end down using Boyle's Law

    Homework Statement Atmospheric pressure is 100 kPa and a depth of 1m in water is equivalent in pressure to 10 kPa. A jam tin, open end down, is forced under water until the water half fills the can. At this stage, how far beneath the surface is the can? (ans is 10 m) Homework...
  30. F

    High School What is the significance of Q in understanding curved mirrors?

    [SIZE="2"]while reading curved mirrors we come across a term denoted as Q(the distance of image from the mirror)but as the image is formed right on the mirror so the distance of the image from the mirror should be zero?? which is of course not the case.
  31. K

    Graduate Particle traveling at 0.5c covers only 1.3E8m in 1 second

    A particle traveling at 0.5c for 1 second covers 1.3E8m (speed=.5*3E8 and gamma=.866) and not 1.5E8. The average speed was then 1.3E8 m/s = .43c and not .5c. What is going on here? Was it travelilng at 0.5c or at .43c?
  32. T

    Fly traveling between car and wall: how many trips?

    Homework Statement A car moving at constant speed of 40 km/h in a straight road which heads towards a wall makes a 900 (90 degree) turn by the side of the wall. A fly flying at constant speed 100km/h starts from wall till car and when it reaches the car turns back and flies towards wall at...
  33. L

    Undergrad What Is the Difference Between Dark Matter and Dark Energy?

    im having a hard time understanding just what it actually is. I've heard about WIMPs and now quirks. But i know we can't see it, but how dose it affect us? Why does it emit no light? I've also heard about the big crunch saying that if there is too much matter in the universe it would...
  34. V

    Darlington pair base current with floating fingers on base

    I was trying a simple Darlington circuit with two Darlington-connected NPN transistors. There is an LED in the shorted collectors, connected to a 5V supply, and the base is open. The trivial objective was to see that when you touch two fingers to the base and the supply positive, the LED turns...
  35. L

    High School What happens to a laser beam in a perfectly reflective box?

    If you could build a box with a reflective inside that no light could escape. If somehow you put a laser in the box and fired the beam and then shut off the laser what would happen? Would the beam continued to bounce off of the insides of the box or would the beam dissipate somehow? If it does...
  36. J

    Bright object in the night sky, possibly Venus

    Saw a reaalllyy bright star-looking object in the sky tonight after looking online, I'm thinking it was Venus. That what all the articles online are leading me to believe. so... Has anyone else seen it? it looks amazing to be honest. I really wish I had a telescope.
  37. A

    Undergrad Is RGBY TV Technology a Game Changer for Color Accuracy?

    I just saw a commercial for http://rgbytv.com/" I understand how additive color mixing works, and how the addition of a yellow channel would allow for the creation of more http://www.ncsu.edu/scivis/lessons/colormodels/color_models2.html#saturation." yellows, but if we only have RGB cone...
  38. L

    AMMC-6220 amplifier showing gain spikes at high frequency

    Gentlemen and ladies, I have an RF device and an in-line amplifier (specifically an AMMC-6220 - http://www.datasheetcatalog.com/datasheets_pdf/A/M/M/C/AMMC-6220.shtml). Certain units develop gain spikes at the high-freq band. They are in very specific frequency locations, and vary in amplitude...
  39. M

    High School Why Do Some Months Have 30 or 31 Days While February Has 28?

    Hy. Why some months have 30 and some 31 days , and february 28? Thanks!
  40. J

    Medical Why does rocking motion have a soothing effect?

    Why is it that a rocking motion gives a soothing effect? I guess it has to do something with brain fluids, but no clear answer.
  41. S

    What determines the unique identity of subsets within universal systems?

    A lot has been discussed/posted about various models/theories to explain consciousness, the systems of laws, fundamental physics, emergence, upward and downward causality etc. However I think too much of these theories focus on GENERAL universals and ultimately on the mechanisms, but not on...
  42. F

    Graduate Pipe orientation for fluid flow on rotating disk

    Here's something simple but also a bit puzzling, let me know if you have any ideas... For clarity, I'll describe three cases before asking the final question (skip ahead if you like). 1. Mounted on a disk are two curved fences, just a few centimetres apart from each other. Between the fences...
  43. P

    High School Why does Mercury move much faster than Pluto?

    why does mercury move with such velocity while pluto is much slower?
  44. D

    Undergrad How Can 1+1 Equal 0 in Certain Mathematical Contexts?

    helo.. We know that 1+1 = 2. but try this out..there is some dummy things goes around here Firstly, we denote 1 + 1 = 1 + \sqrt{1} <=> 1 + \sqrt{(-1)(-1)} <=> 1 + \sqrt{-1}\sqrt{-1} <=> 1 + i*i <=> 1 + (-1) <=> 0 ?? how come 1+1=0 ? and where is the...
  45. N

    Undergrad What is Blondel's theorem?

    tell me somthing about blondels theorem