O Physics: K Meson Decay and Velocity Calculation

[bon]

Homework Statement

A K meson has a total energy of 890 MeV in a laboratory where it decays along
its line of flight into two π mesons. At what speed is the K meson traveling in the
laboratory frame prior to the decay? What are the velocities and energies of the π
mesons in the laboratory frame?

Homework Equations

The Attempt at a Solution

Would the two pi mesons be moving together? If so, I know how to solve the problem...

If they would be - why do they? If not, why not?
Thanks

 

[Andrew Mason]

Homework Statement

A K meson has a total energy of 890 MeV in a laboratory where it decays along
its line of flight into two π mesons. At what speed is the K meson traveling in the
laboratory frame prior to the decay? What are the velocities and energies of the π
mesons in the laboratory frame?

Homework Equations

The Attempt at a Solution

Would the two pi mesons be moving together? If so, I know how to solve the problem...

If they would be - why do they? If not, why not?
Thanks

What are the rest masses of the K meson and $\pi$ mesons? You will need that information to solve this problem.

What is conserved here? Can it be conserved if the $\pi$ mesons are moving at the same speed as the K meson was? If not, can they change speed and still be moving together ?

AM