I haven't answered a question like this in 50 years, since high school Physics, but it seems straightforward enough. The relevant equation, as I recall, is D = ViT + 1/2 (A*T*T).

Your Vi (initial velocity) is 1000 m/s. Convert gravity to m/(s*s) to get your A. Divide this into your Vi to get your T, how many seconds will pass until your velocity is zero.

Your A will be negative, and it's important to subtract the second term from the first, since the object is slowing and not maintaining the Vi. Now just plug in everything and there's your answer in metres.

Has anything changed in 50 years? More important to me, a guy who loves mathematics, got his first two degrees in Computer Science and then Economics, before a third in Psychology, why do I remember this 50 years later?

Thanks for your answer.