1. The problem statement, all variables and given/known data A 4.2 kg object, initially at rest, "explodes" into 3 objects of equal mass. Two of these are determined to have velocities of equal magnitudes (5.0 m/s) with directions that differ by 90 degrees. How much kinetic energy was released in the explosion? (that is what is the energy of the three object systems after the explosions) 2. Relevant equations To be honest, my teacher did not cover this in class so I'm naked in the dark on this one. 3. The attempt at a solution Since they are at 90 degrees to eachother, one would be 5 j m/s and the other would be 5 i m/s. I am not sure where to go from there or where the third factors in.