1. The problem statement, all variables and given/known data A [tex]\pi[/tex]+ meson whose rest energy is 140 MeV is created 100km above sea level in the earth's atmosphere. The pi+ meson has a total energy of 1.5X10^5 MeV and is moving vertically downward. If it disintegrates 2x10^-8 s after it's creation as determined in its own frame of reference, at what altitude above sea level does the disintegration occur? 2. Relevant equations energy conservation. 3. The attempt at a solution I used energy const. to get the velocity of the particle, then attempted to calculate it's displacement which is approximately 6 km and I get approx. 94 km. the correct answer is given to be 93.6, which is not a small error in my opinion.