1ebec223e0dc2bae61abe9e74683776d32540761fa1e9d801f22da3eb5044997ba8140154620723a14fd9c85bb0968b0e09bafb54f4ee7b9

S=vot+½at²
30=8+½×g×t²
4.9t²+8t-30=0
t=1.78