Question

A stone is dropped from the top of a tall building and at the same time another stone is thrown vertically upward from the ground level with a velocity of 20m/s the stones meet exectity 2s after their release how tall is the building

Answer 1

Since the height of the falling stone is the same as that of the projected stone after 2 seconds,

h-4.9t^2 = 20t-4.9t^2
h = 20t = 40