Re: Car acceleration

[Herbert H Gottlieb <herbgottlieb@JUNO.COM>]

> Howdy,
>
> If you think in terms of how the tire deforms as IT pushes BACKWARD
> ON THE ROAD  you will see that, indeed, the static friction force
> THE ROAD applies ON the TIRE is in the FORWARD DIRECTION.
>
> Good Luck, > Herb Schulz  (herbs@interaccess.com)

Herb Schulz
I think that you are confusing STATIC friction with
MOVING friction here. STATIC friction occurs only when the
car's velocity is zero. In such conditions the friction
force direction cannot always be determined until after
a horizontal force is applied to the car. Static friction
is a kinda hindsight calculation that can be fully measured
only when it is no longer being applied.

Herb Gottlieb from New York City
(Where most of our physics textbooks ignore static friction)









On Sun, 03 Feb 2002 10:29:12 -0600 Herb Schulz <herbs@INTERACCESS.COM>
writes:
> > ...
> > c. Friction from the road would be in the reverse direction
> > and could only decelerate the car (which we assume is already
> > initally stopped at the stop sign).
> ...
>
> > Herb Gottlieb from New York City
> > (Where cars do not always stop at stop signs when the police
> > are not around)


Herb Gottlieb from New York City
(Where it's nice to live but I wouldn't
want to be a tourist here)
herbgottlieb@juno.com