While standing at the edge of the roof of a building, a man throws a stone upward with an initial speed of 7.71 m/s. The stone subsequently falls to the ground, which is 14.7 m below the point where the stone leaves his hand.

At what speed does the stone impact the ground? Ignore air resistance and use =9.81 m/s2 for the acceleration due to gravity.
What is the Impact Speed:m/s
What is the Elapsed Time:s