Answer:
 R = v √(2h / g)
Explanation:
This exercise can be solved using the concepts of science, projectile launching
let's calculate the time it takes to get to the water
      y = y₀ +[tex]v_{oy}[/tex] t - ½ g t²
as the stone is skipped the vertical speed is zero
      y = y₀ - ½ g t²
for y=0
      t = √ (2y₀ / g)
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the horizontal distance it covers in this time is
      R = v₀ₓ t
      R = v₀ₓ √(2 y₀ / g)
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let's call the horizontal velocity as v and the height is h
      R = v √(2h / g)