$1.3.4.$ A free-falling body flew past point $A$ with velocity $v_A$. How fast will it fly past point $B$, which is $h$ below $A$?
From the Law of Conservation of Energy: $$ \frac{mv_A^2}{2} + mgh =\frac{mv_B^2}{2} $$ Where, $$ \fbox{$v_B = \sqrt{v_A^2 + 2gh}$} $$
$$v_B = \sqrt{v_A^2 + 2gh}$$