1. The problem statement, all variables and given/known data Pions are part of a class of short-lived particles called mesons which commonly created during the collisions in scientific accelerators or when cosmic rays collide with particles in the upper part of the earth's atmosphere. A type of pion known as a π+ has a mass of 139.6 MeV/c2. One particular π+ was created during a collision in the earth's upper atmosphere and has an total energy E= 1.25 X 105 MeV. As measured in its own frame, it has a life time of 38 nsec before it decays. a) If it decays at a point 146 meters above sea-level, how high above sea-level was the comsic-ray collision that created the pion? hcollision = m 255345.052163 NO HELP: Provide this information in the frame of reference of an observer on earth. HELP: How are the total energy and mass of an object related? b) How long does the particle live in the frame of reference of an observer on earth?? Δtearth = nsec c) In the frame of reference of the pion, how far does it traveled before it decayed? Δxπ = m * 11.39 OK 2. Relevant equations d ' = dγ γ = sqrt (1 - v^2/c^2) E = K - mc^2 K = mc^2[(1/γ)-1] 3. The attempt at a solution I used total energy + rest energy (E + mc^2) = kinetic energy (K). When I solved K for V I found that the particle was moving nearly at the speed of light. .999999999004c (that's 9 9s). I used that speed to calculate my γ = 4.46318e-5. d' = dγ 11.39m = d (4.46318e-5) d = 255199.052163 m The particle decayed 146m about sea level so d+146 = 255345.052163. But it tells me no, so I believe the error might have come in calculating my V. If I can get A, B will be no problem...but I'm stuck. Help!! Thanks!