A smooth spherical object (the first object) is projected horizontally from a point of vertical height $H = 28.71$ metres above horizontal ground with a launch speed (initial velocity) of $u = 22.68 \operatorname{m/s}$
A second identical object is projected from ground level with launch speed (initial velocity) $v$ and at an angle $A$ above the horizontal.
Calculate the value of this launch angle $A$ in radians, if the second object is to have the same horizontal range and the same time of flight as the first object. Take acceleration at gravity to be $g = 9.81\operatorname{m/s}^2$
Attempt answer
$(1)$ Use $t = \sqrt{\dfrac{2H}g}$ to find $t$
$(2)$ $t = \dfrac{2u\sin A}g$ to find $A$