
Originally Posted by
Frog
Gravity is a constant Jim - drop a stone with one hand and at the same time shoot a high velocity rifle with the other (at the same height above ground and zero elevation) and the stone and bullet hit the ground at the same time. OR drop a stone from 32 feet and shoot a rifle from 32 feet above ground and the stone and pellet hit the ground at the same time - 1.41 seconds after you drop / fire.
What velocity change does, is depending on which way you look at it, alter the time gravity has to act on the projectile for a given distance OR determine how far the projectile gets before it hits the ground: what it does not do is alter the time taken to hit the ground because gravity is a constant.
The calculation uses three elements g (gravity), d (distance fallen), and t (time). Know any two of these and you can work out the third - in this case we knew g and d so could calculate t.