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Homework Help: Similar to calculating distance of photon traveling in space?

  1. Apr 4, 2009 #1
    1. The problem statement, all variables and given/known data

    Bullets of mass 1.53 gm are fired in parallel paths at speeds of 244.4 m/s through a hole 1.99 mm. How far from the hole must you be to detect a 1.77 cm in the beam of bullets

    2. Relevant equations

    3. The attempt at a solution

    I feel as though some crucial information is missing (like a word between "1.77 cm" and "in the beam". Am I missing something here? Can someone just give me a clue on where exactly to start? My professor is not the best at explaining the concept behind the problem sets. Thanks in advance.
  2. jcsd
  3. Apr 5, 2009 #2
    OP here.

    So I have tried using Hubble's law, but is this the right approach? Should I be thinking about matter waves?
  4. Apr 5, 2009 #3


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    Staff Emeritus
    Science Advisor

    I imagine that 1.77 cm is the distance between bullets. Is this about resolving some spatial feature at a distance?

    Presumably the 1.99 mm is the depth of the hole?

    Are you doing something about the uncertainty principle by any chance?
  5. Apr 5, 2009 #4
    I figured out the problem. I approached like a single-slit diffraction problem, and after calculating the wavelength of the bullets, calculated the distance to the "screen" to see half of the spread in the beam.

    Thanks though. I sort of wish it had been a universe expansion problem!
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