Concept Simulation 2.2 offers a useful review of the concepts that lie at the heart of this problem. Two rockets are flying in the same direction and are side by side at the instant their retrorockets fire. Rocket A has an initial velocity of +4700 m/s, while rocket B has an initial velocity of +9400 m/s. After a timet both rockets are again side by side, the displacement of each being zero. The acceleration of rocket A is -19 m/s2. What is the acceleration of rocket B?