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Re: A few errors in your reasoning. (archive)

[ Follow Ups ] [ 3-series (E46) Message Board ] [ Msg. Board FAQ ]

Posted by Rudy on October 07, 1999 at 18:27:39:

In Reply to: Re: A few errors in your reasoning. posted by Long Distance on October 07, 1999 at 16:44:39:

: If two cars start at the same velocity, end at the same velocity, have the same deceleration rates and distances (implying same deceleration times) the distance between them when they stop is the distance between where the lead car started braking and the trailing car started braking.

: I used constant linear deceleration, which you did not. I explicitly stated this is what I was doing so where do you get YOUR math from?

Your first comment is right and is what I did: In the first example (2 seconds reaction time), both cars started braking at the same point:
The second car drove at 88ft/s for 2 seconds before braking, that is equal to 176ft and is exactly the distance that separated them originally. Therefore they start braking at the same physical location and end up bumper against bumper both going 0mph.

Your second comment is incorrect however. I used the exact same (linear) decelaration rates that you did.
The way you did it was that if the car went from 60 to 40 in 2 seconds it averaged 40 over those two seconds. The way I did it is that it averaged 50 for 2 seconds. That is very linear, it is just the average of the velocities.

Now all your other comments have merit (I wouldn't bother replying to you if I didn't think you were intelligent and brought up good points), I think I could come up with answers for them (I am not that cocky) but frankly I am tired of this issue. If you want to discuss this further just email me.

Later, Rudy.

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