Question

A ball is dropping from the roof and the window of 3m where a boy observe ball cross window in 0.5sec find the distance of wall above the window

Answer 1

let h be the distance to top of window.
h=1/2 g t^2 or
t=sqrt(2h/g)

but
h+3=1/2 g (t+.5)^2
h+3=1/2 g (t^2+t+.25)
h+3=1/2 g (2h/g+sqrt(2h/g)+.25)
now do your algebra, put this in the form of a quadratic and solve for h. Yes, it will take a pad of paper of algebra.