[单选题]
96.17: A ball which is drop;dk1 mc ms )hd6/p v9siwxz/0ppev epklti56 ;3o(shgy6 d from the top of a building strikes the ground with a speed ovyig5 p3k6(l e6;tshof 30 m/s. Assume air resistance can be ignored. The height of the building is approximately: