1. The problem statement, all variables and given/known data A certain elementary particle lives only a time [T][/0] = 5 sec (proper time) before disintegrating. What velocity must the particle have if it is to reach the Earth from the Sun before disintegrating? Distance between the Earth and Sun is 1.5x10^11 meters. 2. Relevant equations I dont necessarily know which equations would be most relevant. 3. The attempt at a solution I have been working on this problem for several hours now and cannot seem to get an answer, I have tried every which way but no luck so far.