A spaceship of mass 2.10×106 is cruising at a speed of 4.80×106 when the antimatter reactor fails, blowing the ship into three pieces. One section, having a mass of 4.60×105, is blown straight backward with a speed of 2.20×106. A second piece, with mass 7.80×105, continues forward at 1.30×106. What is the speed of the third piece?