Thread: Discussion A non-aerodynamic proof that a lifting wing pushes down on the earth View Single Post
Nov 16, 2012, 03:50 PM
t=1007606
Joined Dec 2006
500 Posts
Quote:
Quote:
 Originally Posted by ShoeDLG I don't understand what you're saying. If you have a string of boxcars that form a closed loop, there is no way for the translational momentum of that string to change (as long as it stays on the track).
I was talking about the fact that the train track is stuck to the medium from which you are applying your force from (the ground).

It should be noted that in your example (due to the ground) there were two forces applied. One by you and one at the centre of the axis by the ground.
If it were a free body where the track was on a steel plate that could slide on the ground , frictionless) then when you apply a push, the trains will move in an angular and Translational way.

The air and aircraft are both free.
Getting back to the train tracks. You created an example where the Track could not move in a translational way due to the way you set it up, and suggest that it is Possible to add Angular momentum to a body with out there being any Translational momentum. But it was not evident to most that this example is not similar to the Aircraft and the Air it is flying in due to the fact the train tracks are stuck to the ground.

You can not add angular momentum to a free body by way of one single application of force without there being a translational component. However you can (Theoretically) do the reverse.