Answer:
I believe it's 8.09 seconds, but I'm rusty on my physics.
Step-by-step explanation:
The equation for solving the time it takes for an object to fall is
So multiply the distance times 2, and you get 642 meters. Then you divide by gravities acceleration constant, 9.8, and you get 65.51. Finally,
, and you get 8.09 seconds.
I pulled the equation off of wikipedia and I'm unsure if it's the correct one, so hopefully this is correct. :/