Question 1208245
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When a massive body falls from the height h, it has velocity of {{{sqrt(2gh)}}} directed vertically down, when hits the ground.



Since in your problem the coordinate axis is vertically up, you take velocity with the sign "minus",


so, your answer in this problem is


    {{{V}}} = {{{-sqrt(2*g*h)}}} = {{{-sqrt(2*9.8*15)}}} = -17.1464282 m/s.
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Solved, with explanations.