Answer:
1/2 m v^2 = m g H conservation of energy
H = (v^2 / (2 * g))^1/2 = (14^2 / 19.6)^1/2 = 10 m
H = 1/2 g t^2 time to fall 10 m
t = (2 * H / g)^1/2 = (20 / 9.8)^1/2 = 1.43 sec
Total time in air = 2 * 1.43 = 2.86
You can also use 2 a S = V0^2 since final velocity = 1.43 * 9.8 m/s = 14 m / s
and 2 a S = 2 * 9.8 * 10 = 196 m^2 / s^2 which is V0 squared
