1. The problem statement, all variables and given/known data In an explosion the two identical trolleys, each of mass m, were initially at rest. Find the total momentum of the trolleys after the explosion. 2. Relevant equations Conservation of momentum. 3. The attempt at a solution Well, I assumed both trolleys to be particles in 2D-motion, and since they have the same mass and were both subjected to the same explosion, and thus were given the same acceleration, the total momentum should be zero. But, a friend of mine said that it could not be determined from the given. Who's right?