# Brakes G60's vs UFO's and other combos............

Bernie Benz b.benz at charter.net
Tue Feb 17 11:57:56 EST 2004

Think harder, Dan.

Your lesson in "physics phacts" is irrelevant to the point of the
discussion, that being the relative temperature rise of the braking
components.  Neglecting the very slight additional heat loss during an
extended breaking time, the temp rise is independent of time, in the
practical sense.  Your erroneous initial point, and one that you have been
backing away from since, was that the temperature rise is not a function of
the kinetic energy absorbed, but rather the rate of absorbption.

Bernie

> From: Dan Cordon <cord4530 at uidaho.edu>
> Date: Tue, 17 Feb 2004 08:19:02 -0800
> To: Bernie Benz <b.benz at charter.net>, 200q20v <200q20v at audifans.com>
> Subject: Re: Brakes G60's vs UFO's and other combos............
>
> Bernie Benz wrote:
>> Dan, you may wish to rethink your "power logic".  New math, new physics?
>>
>
> Sure....power is the time rate of change of energy. Or, average power is
> energy divided by the time taken for that energy flow to happen.
>
> Slowing a particular car - fast or slow - will require the same amount
> of energy. Unless this happens *really* slow, the majority of this
> energy will end up as thermal energy going in to the brake components.
>
> So, if the same amount of energy is transferred in both circumstances,
> but one happens over a shorter time, then more power occurs in the
> faster time interval.
>
> Look at the flip side......accelerating from 0-60 mph. You must agree
> that more power transferred to the ground will accelerate the vehicle to
> 60 mph faster. However, once going 60 mph, the same car will have the
> same kinetic energy - regardless of how fast it got there. F=m*a, and
> conservation of energy works in both directions. Old math, and old physics.
>
> --
> Dan Cordon
> Mechanical Engineer
> University of Idaho - Engine Research Facility
>
>