two rock are thrown off the edge of a cliff one is thrown horizont at a speed of 25 m s the other dropped straight down. which stone will hit the ground first? why?

Answer 1

in the vertical direction the motion of the two rocks is identical. They accelerate down with acceleration -9.81 m/s^2

The fact that one of them is moving with constant velocity (there is no force in the x direction) is irrelevant to the motion in the vertical direction

Therefore they hit simultaneously.