1. The problem statement, all variables and given/known data A train engine of mass ##m## is chugging its way around a circular curve of radius ##R## at a constant speed ##v##. Draw a free body/force diagram for the train engine showing all of the forces acting on it. Evaluate the total vector force acting on the engine as a function of its speed in a plane perpendicular to its velocity ##\vec v##. You may find the picture of the train’s wheels useful. Note that they are notched so that they fit onto the rails – the thin rim of metal that rides on the inside of each rail is essential to the train being able to go around a curve and stay on a track! Draw a schematic picture of the wheel and rail in cross-section and draw in the forces using the force rules we have learned so far that illustrate how a rail can exert both components of the force needed to hold a train up and curve its trajectory around in a circle. Discussion: What is the mechanical origin of the force responsible for making the train go in a curve without coming off of the track (and for that matter, keeping it on the track in the first place, even when it is going “straight”)? What would happen if there were no rim on the train’s wheels? 2. Relevant equations Newton's Second Law Circular Motion 3. The attempt at a solution This is the free body diagram I drew: But besides this, I don't know what are the forces that are actually acting on the train. Can someone guide me through the exercise? And about drawing a schematic picture of the wheel and rail in cross-section, I didn't quite get how I should do that.