Question

A stone is thrown vertically downwards from a building with an initial speed of 4m/s.It reached the ground after 5 s. (a) whats the height of the building h?

Answer 1

using g=10m/s^2, we have

h - 4t - 5t^2 = 0
h - 20 - 125 = 0
h = 125 m

Answer 2

h = 145 m ?.

Answer 3

132.5