Assignment:
A spaceship of mass 2.3*10^6 kg is cruising at a speed of 4.4*10^6 m/s when the antimatter reactor fails, blowing the ship into three pieces. One section, having a mass of 5.1*10^5 kg, is blown straight backward with a speed of 2.1*10^6 m/s. A second piece, with mass 7.6*10^5 kg, continues forward at 1.1*10^6 m/s. What is the speed of the third piece in m/s?