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  1. J

    Glass is not a liquid?

    Thanks Dirac :)
  2. J

    Glass is not a liquid?

    Can you please point me to a video? Searching with the keywords (guys sucking liquid water/juice balls) you mentioned points me to weird videos :) Unless there is an external force (gravity or something else) to overcome the surface tension, any matter would retain its shape. In this case...
  3. J

    Glass is not a liquid?

    Is water liquid at zero gravity?
  4. J

    Glass is not a liquid?

    That's what all the web sites say as a myth. They designed the glass pane bottom thicker for stability. http://math.ucr.edu/home/baez/physics/General/Glass/glass.html
  5. J

    Glass is not a liquid?

    Since my high school days, I learned that glass is a liquid. (Science naive students thought glass is solid, and the smarty pants knew it was actually a liquid:) Yesterday, while I was telling this interesting fact to my daughter, my wife argued that glass is solid. I googled to explain them why...
  6. J

    Physics of ABS brake system

    I was trying to explain the ABS brake system to my daughter, then this question popped up. http://auto.howstuffworks.com/auto-parts/brakes/brake-types/anti-lock-brake1.htm I understand the ABS brake system in general, as the above web site says, The question I have is, why is the...
  7. J

    Gravity evidence

    Do we have evidence to support gravity is a wave (like the interference pattern for em wave)? Do we have evidence to support the gravity waves travel at the same speed of em waves?
  8. J

    We never really touch anything?

    Is it only electron repulsion, or there is proton repulsion too? If you push someone, and if he falls down, the whole atoms moved. Why a touch doesn't cause an momentarily electric current?
  9. J

    What causes the moon to be bright at night?

    well, I have a telescope. I look at moon at midnight and I look at a nearby mountain at the mid noon. I sit in a closed dark room and through my eyepiece, I see only the moon or the mountain - no other background. I see the moon brighter.
  10. J

    What causes the moon to be bright at night?

    To eliminate the effect of perception/pupil, let's keep a moon rock in a dark room and the room has a narrow slit for the sun light to fall on the rock. I don't think you would see the moon rock as bright as the moon. Also we can sit in a dark room and look at a mountain through a window (with...
  11. J

    What causes the moon to be bright at night?

    Thanks for your answer. I'm comparing between the moon rock in the moon and the moon rock that was brought to the earth. Why wouldn't a moon rock brought to earth does not reflect as much as it was in the moon? Also, does an astronaut landed on the moon see the exact bright and dark pattern...
  12. J

    What causes the moon to be bright at night?

    I know it's the reflection of the sun light. But why? the moon is full of dirt and rock and how does it give a silvery white glow? A mountain (on earth) with dirt and rock doesn't glow with sunlight reflection. The astronauts who landed on the moon didn't see the moon shiny white.
  13. J

    Another Gravity question

    But the force did some work on the mass, right?
  14. J

    Another Gravity question

    If gravitational force act on a mass, shouldn't the gravity get reduced, since the force was used to move the mass?
  15. J

    Questions on gravity

    What is the wavelength and frequency of gravity wave? Does gravity wave theoretically have properties that EM waves exhibits? - like diffraction, interference? If a mass suddenly converted to all energy, (E=mc2), what happens to the gravity waves that is already propagated? Wherever the...
  16. J

    Life-saving 'Pole' for Cliff-edge drop

    Won't a safety net do a better job? How do you make sure the person won't land in the middle of the pole? Imagine a man landing on the pole, with legs on both sides...
  17. J

    What happens if

    let's assume container is electrically neutral and no particles could escape it.
  18. J

    What happens if

    Let's say, I put x number of free electrons and x number of free protons into a jar, close the lid, shake it for a while. Do I get x atoms of Hydrogen? Does the each electron start revolving around each proton? If not, why and what do we need to do to make Hydrogen out of it (changing pressure...
  19. J

    Gravitation force

    I'm talking about F = G*m1*m2/(d^2). If d is zero, won't the F be infinite? Or, is there a lower limit to d between two molecules/atoms, that eventually puts an upper limit to F?
  20. J

    Gravitation force

    If the distance between two objects is zero, won't there be infinite gravitational attraction force between them? How would the objects can get separated?
  21. J

    Hourglass on the Moon

    Doesn't it also depend on how fine grained the sand is, and also the radius of the middle portion of the hour glass too? I think the slower-hour-glass-in-moon is true only if the sand is freely falling. Here it's controlled. It would be slower - but how slow would depend on the physical...
  22. J

    Reason for value of c

    In theory, how do we come up with the permeability and permativity of free space?
  23. J

    What is mass?

    Is there anything that satisfies only one of the above condition? - like, has mass and do not occupy space - or - has no mass and occupies space.
  24. J

    Helium and a tuning fork

    Since the OP's question seems to be answered, I use the same thread for a related question. Why is tuning fork U/Y shaped?
  25. J

    Why does our planets orbit?

    What's the explanation of the earth's elliptical orbit, rather a circular orbit?
  26. J

    Cold Black Sun

    yeah, but the houses are still too expensive here. I was trying find some real estate cheaper, without compromising the climate.
  27. J

    Cold Black Sun

    Does there an orbit exist in the (non-earth) space around the sun where we have california like weather/temperature, wearing normal clothes, and live there normally (if we carry large amount of oxygen an food?)
  28. J

    White and silver

    To avoid the angle of incidence/reflection factors,. let's take the case of a perfectly spherical shaped silver object. Shouldn't silver color closer to perfect white (by the definition of white color) color, than the traditional white color, bacause it absorbs the lesser of the incident light?
  29. J

    White and silver

    What's the difference between white and silver color? If both the sufaces are reflecting all the light frequencies, why do they look different?
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