Re: [Phys-l] Static vs kinetic friction

[Bernard Cleyet <bernardcleyet@redshift.com>]

> So can the kicked cart stop during
> the turnaround because of this effect?


I have observed this often and I suspect many others.  For example a  
mechanical oscillator with Coulomb friction will stop at an other  
than the equilibrium position.

I have attached a cart friction accessory to a driven cart acting as  
the mass of a spring oscillator.   The driver was an attached (as the  
support) high Q and energetic pendulum.  The effect is quite  
interesting.  As the pendulum decays (rings down) the delay in the  
movement of the periodically stopped cart increases.  Since I don't  
have a site, I refer to Peter's flip-flop pendulum for the analysis  
of a similar pendulum

http://adsabs.harvard.edu/abs/1997AmJPh..65.1067P


bc will send a PDF attachment for those unable to access.

On 2009, Oct 12, , at 09:17, John Clement wrote:

> This would only have an effect if
> the gravitational force component along the ramp is greater than  
> kinetic
> friction, and less than static friction.  So can the kicked cart  
> stop during
> the turnaround because of this effect?   I suspect that the static  
> friction
> may require a stationary period of time, but an instantaneous stop  
> may not
> be sufficient to fully activate the effect.  I suspect the friction  
> may
> increase slightly during the turnaround, but no to the maximum  
> static value.
> This is a tricky experiment, but perhaps someone already has  
> experience with
> the answer.