So a stone is thrown vertically upward with a speed of 10.0 m/s from the edge of a cliff 65.0 m high. 

So, just making sure I have all my variables right 

Vinitial: 10 m/s 

V: 0 m/s 

g: -9.8 m/s^2 

y= 0 m 

y initial: 70.10 m 

I got 70.10 m by doing 10^2/2(9.8)= 5.10 and added that to the cliff's height because of the ball being thrown up in the air so that equals 70.10 m... is that correct? 

Also, I had to find how much later does it reach the bottom and tried using the quadratic equation for 1/2gt^2 + Vinitial(t) + y initial 

I got 2. something seconds but that wasn't the right answer. 

It was 4.8 s. What am I doing wrong???