Strong or weak force??

R0CC0

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.

gomboc

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?

R0CC0

So in this case weak force?

gomboc

The weak force is the only interaction that can change the flavour of a quark. The strong force can't.

R0CC0

Righto Got it now. Thanks!