Re: [Phys-l] Turning effects of a moving bike

[John Denker <jsd@av8n.com>]

On 08/19/2008 08:35 AM, Bob Sciamanda wrote:

> The point of contact between tire and road is NOT an inertial origin. 
> Torques relative to this accelerating origin are not equal to the time rate 
> of change of system angular momentum.  

That's all true, and it's good advice in general ... but I don't see
how it answers the question.

The way I read the question, it asked why using the center of mass
was /different/ from using the contact point as the datum.  I don't
see how mentioning "non inertial" explains the /difference/.  Neither
the CM nor the contact point is inertial.