Re: shifting one's weight

[guntbert@cut.big.ac.at (Guntbert Reiter)]

*"shifting one's weight"*
James Mclean wrote on Wed, 5 Feb 1997 10:45:47 -0800 (PST) :

> Now extend the arm.  Internal forces cannot move the center of mass of a
> system.  Therefore, if the board were on a frictionless surface, the =
mass
> would move right and the board would move left.  But the board is
> constrained not to move: the pivot exerts a frictional force on the =
board

Here I notice a difference between you model and a bike: the bike
CAN "move" so that the center of mass keeps its position right
above the line between the contact-points of wheel and floor. In
fact the bicycle is not shifted but tilted. Try this: rolling at
whatever speed slowly tilt you upper body to the right side and
you will notice that the frame of the bike is tilted to the left.

In this position you will also notice a force on the handlebar
which pulls the "upper"(=3Dright) handle away from you - regardles
of your speed - with some traing you can to that even in the
halt.

Bye, bye
	Guntbert
-------------------------------------------------
Guntbert Reiter, Graz, Austria
e-mail     : guntbert@cut.big.ac.at