Question

You landed a great summer internship as the assistant to Christopher Nolan's technical director for the upcoming Batman movie. During one sequence, Mr. Freeze has managed to knock Batman off of the front of a train. He's also frozen the front face of the train solid, so Batman has no grip on the train and is about to start sliding down. In the midst of this action, Robin has successfully taken control of the train and quickly realizes that he must do something to rescue Batman. The script calls for Robin to accelerate the train so that Batman can keep from slipping and have time to gain a foot