A kaon (denoted K0) is an unstable particle of mass 8.87 X 10-28 kg. One of the means by w...

A kaon (denoted K0) is an unstable particle of mass 8.87 X 10-28 kg. One of the means by which it decays is by spontaneous creation of two pions, a π+ and a π-, The decay process may be represented as

Both the π+ and π- have mass 2.49 X 10-28 kg. Suppose that a kaon moving in the +x direction decays by this process, with the π+ moving off at speed 0.9c and the π- at 0.8c. (a) What was the speed of the kaon before decay? (b) In what directions do the pions move after the decay?