Thread title amended to be more descriptive of the problem
A ball is shot from ground into the air. at height 8.3m, its velocity is 7.8i + 6.5j. Find Maximum height rise, horizontal distance traveled and magnitude of velocity just before the ball hits the ground.
The Attempt at a Solution
So i got the total height. i got 10.45. My question is in part of magnitude of velocity as it hits the ground. So if the ball reaches a height of 10.45m, then would i use v^2=vo^2+2a(dy) to find final vertical component of velocity. So if the ball reaches a maximum height of 10.45m. then isn't dy=10.45? it says in the solution that i should use 8.3m for dy, but why? if the ball is at 10.45?