Solve a Golf Ball Physics Problem: Calculate Velocity After 2.84s

[yankee]

A golf ball is released from rest from teh top of a very tall building. Choose a coordinate system whose origin is at the starting point of the ball, and whose y-axis points vertically upward. The acceleration of gravity is 9.8 m/s^2. Neglecting air resistance , calculate the velocity of the ball after 2.84s. ANswer in units of m/s.
---ok basically i have tried this question about 3 times and each time i have gotten it wrong. The first two answers made absolutely no sense and the third answer i got was 185.3543
this is how i did it:
Vf= 9.8m/s^2(2.84s)^s
= 60.27392
then i did
60.27392^2= 2(9.8 m/s^2x)
i got 185.3543
----
please reply asap i have no clue how to solve this- i thought i was correct but apparently not. what formulas should i use? How would i go about to getting the answer? THANKS SO MUCH

 

[BunDa4Th]

V = V_o + GT
DeltaY = V_oT + 1/2GT^2
DeltaY = Y_f - Y_i

V_o = 0
Y_i = 0

G = -9.8

I hope that help.

It seem you made gravity 9.8 when it should be -9.8 since gravity is going down so it would be negative.