Calculating Velocity and Time of a Falling Object from a Given Height

[openavalin]

Jen is standing on top of a 52 meter high building. She threw a rock straight downward at 18m/s.
How fast will the rock be traveling when it hits the ground?
Determine how long it will take for the ball to hit the ground?

my attempt: I got 31.45m/s as the speed of the rock and 1.402 seconds to hit the ground, but I don't think I did it right. Can someone please help me out?

 

[phinds]

Show HOW you got what you got (and in future, use the homework template the way you agreed to do when you signed up for this forum).