On Sun, 09 Sep 2012 17:15:14 +0100, polygonum
wrote:

but if it wasn't for friction, the wheels would simply spin on the
ground.


T'aint necessarily so. The non-flatness at a macro scale would be
sufficient without any 'real' friction being needed.

Take it small enough and that's all friction is. So, without friction,
you'd be ****ed. We'd all be ****ed.
What's 'real' friction when it's at home?