A person standing on top of a building of height H throws a ball vertically upward with initial velocity Vj. He then throws an identical ball vertically downward with initial velocity -Vj. Compare the velocities of the two balls just before they strike the ground. Write equations to explain your reasoning.
Velocity at time T=4.9t^2
The Attempt at a Solution
I know that at the point when the first ball gets back to y=0 the velocities are the same. I do not know how to keep comparing them to show the balls are the same just before they hit the ground. Any help is appreciated!