Math/Physics
posted by Tyler .
John is driving at a constant speed of 20.0 m/s when he passes Jane, who is traveling in the same direction at 15.0 m/s at the moment that John passes her. If Jane is accelerating at 2.0 m/s2, how far will Jane drive before she catches up to John? How much time passes from when John passes Jane until Jane catches back up with John? (You can assume all motion is on flat, level ground.)

John distance=20*time
Jane distance=15*time+1/2 a time^2
set them equal, solve for time
then solve for either distance in that time. 
Why the 1/2 in 1/2*a*time^2?