Your best approach is to use acceleration equals 9.81 meters per second per second. From there, you can integrate your equation until you get a velocity equation and finally the displacement equation. All you need to know is acceleration and once you integrate using initial velocity as zero (or v(0)=0), you can set the displacement equation equal to 500. You can also use basic physics kinematic equations to find the time, and then plug in the time to your velocity equation to find the final velocity.
Note: t=time
A(t)=9.81
V(t)=9.81t+C, but we know C=0 because V(0)=0
D=4.9t2