A grenade with a mass of 0.4 kg is thrown with an initial speed of 11 m/s at an initial angle of π/7 rad relative to the horizontal. When it is at the exact apex (top) of its trajectory, it explodes into two fragments, one has a mass of 0.1 kg the other has a mass of 0.3 kg. A total of 80 kJ of kinetic energy is added to the fragments. The velocities of the two fragments are completely horizontal at the instant of the detonation. Where do the fragments land?