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Starting to forget my physics: silly energy question

  1. Aug 21, 2005 #1
    if two equal masses with equal speed are traveling towards eachother, do they have 0 total energy, or twice the energy of one mass?
    I know they will have 0 total momemtum, but I can't remeber if adding their energy is a vector thing or not.
  2. jcsd
  3. Aug 21, 2005 #2


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    Gold Member

    Its not a vector problem and how can they have 0 momentum if they are both in motion.
  4. Aug 21, 2005 #3
    If they are considered as a system then the system has zero net momentum. Each individual component has its own momentum vector according to its path. Their kinetic energy is the sum of the kinetic energies of each piece, KE is a scalar and not a vector.
  5. Aug 21, 2005 #4
    ok, thats what i was thinking but wasn't positive.
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