1. The problem statement, all variables and given/known data There is a train travelling along a circular track. Which rail does the centripetal force act on (Inner or Outer) and what 2 factors determine the stress on each wheel. 2. Relevant equations 3. The attempt at a solution So I was thinking it might be the outer, but I am not sure and as for the wheels, I imagine one of the factors is the train's weight, as for the other, not sure.