With the engines off, a spaceship is coasting at a velocity of +250 m/s through outer space. The ship carries rockets that are mounted in firing tubes, the back ends of which are closed. It fires a rocket straight ahead at an enemy vessel. The mass of the rocket is 1200 kg, and the mass of the spaceship (not including the rocket) is 2.0*10^6 kg. The firing of the rocket brings the spaceship to a halt. What is the velocity of the rocket? I used the equation vcm=m1*v1+m2*v2 divided by m1+m2. The answer I got is wrong. Am I using the right equation? Please Help ASAP!!