An object is thrown from a height of 8.0m, with a horizontal velocity of 28.0m/s. How far will this object travel horizontally before hitting the ground?

3 answers

t =sqrt(2h/g)
s =vt
I really did not get the formula
Please explain it to me
http://www.physicstutorials.org/home/mechanics/1d-kinematics/projectile-motion?start=1