A projectile of mass 20.6 kg is fired at an angle of 59.0^\circ above the horizontal and with a speed of 76.0 m/s. At the highest point of its trajectory the projectile explodes into two fragments with equal mass, one of which falls vertically with zero initial speed. You can ignore air resistance. How much energy is released during the explosion? Conservation of momentum and Kinetic Energy Equation Change in KE=Kf-Ki So. I used conservation of momentum to find that the speed of the top fragment is 152 m/s. I plug it into the kinetic energy equations but my answer is not accepted on my hw site. I plugged in... Change in KE= (.5)(10.3)(152)^2-(.5)(20.6)(16)^2=59492.8 J which is wrong.