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Homework Help: Strong or weak force?

  1. Mar 10, 2012 #1
    Strong or weak force??

    1. The problem statement, all variables and given/known data
    So all I want to know is how you tell if it is a strong or weak force interaction.
    e.g. K^+ = pi^0 + pi^0 + pi^+ (all mesons)

    So i determined that the energy was concerved:
    493.7-135-135-139.6=84.1MeV

    baryon and Lepton numbers are also conserved
    (0)=(0)

    Now having determined that the interaction is possible, how do I tell if it is via strong or weak force.
     
  2. jcsd
  3. Mar 12, 2012 #2
    Re: Strong or weak force??

    The key here is to look at the quark content of the reactants and products. A positive kaon has an up and an anti-strange quark. Yet none of the pions contain a strange/anti-strange quark.

    What is the only interaction capable of changing the flavour of quarks?
     
  4. Mar 12, 2012 #3
    Re: Strong or weak force??

    So in this case weak force?
     
  5. Mar 12, 2012 #4
    Re: Strong or weak force??

    The weak force is the only interaction that can change the flavour of a quark. The strong force can't.
     
  6. Mar 12, 2012 #5
    Re: Strong or weak force??

    Righto Got it now. Thanks!:smile:
     
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