Respuesta :

Answer:

4.04 s

Explanation:

h = vi + 1/2 a t ^2

HERE  h = 80 m , vi = 0 , a =9.81 m/s^2

80 = 0 + 1/2 × 9.81 × t ^2

80 = 4.905 t^2

t^2 = 80/4.905

t ^2 = 16.30988

t = square root of 16.30988

t =  4.0385 s

t = 4.04 s