# Light speed (possibly done to death)

by cappsie
Tags: death, light, possibly, speed
 Thanks P: 1,948 The correct formula to add a passengers speed (relative to the train) $v_{relative}$ to the speed of the train $v_{train}$ to find its speed relative to the ground $v_{passenger}$ , assuming both passenger and train are moving in the same direction, is $$v_{passenger}=\frac{v_{relative} + v_{train}}{1+\frac{v_{relative}\times v_{train}}{c^2}},$$ where c is the speed of light.