physics
posted by dale .
A brick is thrown vertically upward with an initial speed of 5.00 m/s from the roof of a building. If the building is 112.0 m tall, how much time passes before the brick lands on the ground?

a = g = 9.8
V = Vinitial + a t = 5  9.8 t
h = Hinitial + Vi t +(1/2)at^2 = 112 + 5t4.9t^2 = 0 at the end
so
112 + 5 t 4.9 t^2 = 0
4.9t^2 5 t 112 = 0
solve quadratic, use positive t