A stone falls from a height of 60m on the ground the height h after "x" second

Question

Q#1\

A stone falls from a height of 60m on the ground the height h after "x" second is approximately given by h(x) =40-10x whats the height of stone when x=1sec x=1.5sec when does the stone strike the ground A stone falls from a height of 60m on the ground the height h after "x" second is approximately given by h(x) =40-10x whats the height of stone when x=1sec x=1.5sec when does the stone strike the ground?

Answer 1

??????????? how kan it fall if its "on the ground" ??????????