1. The problem statement, all variables and given/known data An object, with mass 71 kg and speed 23 m/s relative to an observer, explodes into two pieces, one 5 times as massive as the other; the explosion takes place in deep space. The less massive piece stops relative to the observer. How much kinetic energy is added to the system during the explosion, as measured in the observer's reference frame? 2. Relevant equations Equation 1: m1=5m2 Equation 2: (1/2)mv^2 Equation 3: mv1 (intiial) + mv2 (initial) = mv1 (final) + mv2 (final) 3. The attempt at a solution I used equation 1 go determine the masses of the two exploded pieces and determined the initial kinetic energy by plugging in 71 kg and 23 m/s into equation 2. I then plugged in all the data into equation 3, where mv2 (final) is equal to 0, and solved for mv1 (final). I then plugged the final velocity for object 1, as well as the mass, into equation 2. When I subtracted the initial kinetic energy from the final kinetic energy, I came up with 93897.5 J.