Halliday, Resnick & Walker — Center of Mass and Linear Momentum: Problem 13

13 A shell is shot with an initial velocity \(\vec{v}_0\) of 20 m/s, at an angle of \(\theta_0 = 60^\circ\) with the horizontal. At the top of the trajectory, the shell explodes into two fragments of equal mass (Fig. 9-32). One fragment, whose speed immediately after the explosion is zero, falls vertically. How far from the gun does the other fragment land, assuming that the terrain is level and that air drag is negligible?