posted by Natalie .
As two trains move along a track, their conductors suddenly notice that they are headed toward each other. The figure below gives their velocities v as functions of time t as the conductors slow the trains. The slowing processes begin when the trains are 240 m apart. What is their separation when both trains have stopped?
Do I use v= v_0+at or x-x_0=(v_0)(t)+0.5at^2 to solve this?