How long in seconds does it take to hit the ground after a ball is dropped from a height of h70 m?

neglecting air resistance,

distance = 1/2 gt^2 where g = acceleration of gravity = 9./8 m/sec/sec

70 = 1/2 (9.8) t^2

14.28 = t^2

t = square root 14.28 = 3.78 seconds