Re: Car acceleration

[Brian Whatcott <inet@INTELLISYS.NET>]

At 10:20 PM 2/5/02, Bob Carlson wrote:

> > > This is confusing to me and I suspect confusing to students.  Why not
> > > identify the force that is really doing work and go from there?
> >
> > In this particular case I wouldn't do that because (ignoring air
> > resistance and rolling resistance) there *is* no force that is
> > doing "real work" on the car.
> >
> >
>
> Then you would say there is no real work being done?   And no real change in
> kinetic energy?  I would say there is a real force doing work and this comes
> from the drive axle applying a normal force on the car.
>
> Bob Carlson


True believers avoid facing this particular fact by noting it is inside the
car, and the force exerted on the axle bearings which provides the car with
a way to accelerate also motivates the motion of the wheels and axles - so
that although corresponding with reality, it is not 'clean' and requires
insight into the mechanism in an 'unphysics' way.


Brian Whatcott
  Altus OK                      Eureka!