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  1. J

    Running jump

    But, as someone asked before, why don't they run faster? Could it be because, they need to turn around and push with both the legs for maximum power? That explains why in pole-vault, they run with their maximum speed. In pole vault, not much leg power needed, and they get time to turn around...
  2. J

    What kills you when you fall down?

    Does that mean, 0mph to 60mph in 1 second can do the same damage to our body as 60mph to 0mph in 1 second? I don't hear anybody died in Formula One, because they started too fast.
  3. J

    Speed of sound in substances

    Does the frequency of the sound matter?
  4. J

    Speed of sound in substances

    Speed of sound should be same as the propagation speed of a mechanical vibration in the medium, right?
  5. J

    How does an eraser work?

    How does an eraser (rubber, for non-US) work? Any why it works only for pencil(or graphite) , not for pen?
  6. J

    Question regarding a car crash

    Is it theoretically possible to jump up from a free-falling elevator?
  7. J

    Weight at noon & at night !

    Is astrology based on science?
  8. J

    The cause of Friction between objects

    You mean, if I cut an iron rod into two, and if I put the two pieces together, with nothing absolutely in between, they will become one piece again?
  9. J

    How does sound travel?

    Can I say the sound frequency is also a factor of the medium? Can I make an an ultrasound wave human-audible by passing it through a different medium? Also, does the frequency change over a distance?
  10. J

    How does sound travel?

    True. I should admit, when I think deep into physics and chemistry, I just feel myself as just a bunch of atoms and subatomic particles, grouped together by some interatomic forces. That makes me miss some other important aspects, but you know, helps me less fearful about my own death:)...
  11. J

    How does sound travel?

    How does sound travel??? Does sound travel merely by vibration of particles in the media? To my imagination, the sound propagates as follows: The atom/molecule close to the sound source moves towards the neighbouring sides. The repulsion from one electron in the atom moves the electron in...