Originally Posted by ShoeDLG
When Newton says that an object's rate of momentum change is equal to the unbalanced force acting on it, he is referring to the object's linear (or translational) momentum, not it's angular momentum.
I don't think anyone has yet tried to suggest that the lift force acting on a wing is equal to the air's rate of angular momentum change (or the air's rate of energy change).
It applies to the Angular.
Now imagine your train track was a free body, and you applied a force in one direction same as before. But not for a full revolution maybe for just 5deg of the rotation of your train link. This time you will see an angular and translational momentum result.