1. The problem statement, all variables and given/known data A locomotive (6.4 × 105 kg) is used to pull two railway cars (Figure 11). Railway car 1 (5.0 × 105 kg) is attached to railway car 2 (3.6 × 105 kg) by a locking mechanism. A railway engineer tests the mechanism and estimates that it can only withstand 2.0 × 105 N of force. Determine the maximum acceleration of the train that does not break the locking mechanism. Explain your reasoning. Assume that friction is negligible. 2. Relevant equations F = ma 3. The attempt at a solution To start I decided that it can only withstand 2.0 × 105 N of force in any direction, but the train will never move backwards, so the net force can only be 2.0 × 105 N in one direction, the right. (the diagram shows the train moving to the right). Furthermore, all the objects will be moving in on direction all at once. My textbook states that if they all move together then they must all have the same acceleration (by adding the masses of the carts and the engine together and dividing by the force that causes all the carts and the engine to move in the first place). So when I try to do I get an answer around 0.1 when the answer in the back is 0.56 m/s^2. Why is that so? What is wrong with my method and understanding of these types of questions? Any help is appreciated. Thanks again.