Q. A mortar fires a shell of mass at speed. The shell explodes at the top of its trajectory (shown by a star in the figure) as designed. However, rather than creating a shower of colored flares, it breaks into just two pieces, a smaller piece of mass and a larger piece of mass. Both pieces land at exactly the similar time. The smaller piece lands perilously close to the mortar (at a distance of zero from the mortar). The larger piece lands a distance from the mortar. If there had been no explosion, the shell would have landed a distance from the mortar. Suppose that air resistance and the mass of the shell's explosive charge are negligible. Determine the distance from the mortar at which the larger piece of the shell lands.

Express d in terms of r.