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Re: Solve speeding by limiting cars!



Hactar (Eben@Gate.Net) wrote:
: In article <snagiel-1411952325550001@turm-a27.resnet.emory.edu>,
: snagiel@emory.edu (Shahak Nagiel) wrote:

: >> In article <4895bo$oar@nntp.atlanta.com>,  <dwarner@atlanta.com> wrote:
: >Many drivers seem to forget a
: >fundamental law of physics which states that the kinetic energy is equal
: >to mass (the car's weight) times velocity SQUARED.

:   Yes.

Actually that's twice the kinetic energy (E=0.5*m*v^2)
And, actually it is a relationship that follows from fundamental laws

: >Regardless of the
: >car's mass, the point is that for doubling your speed, the momentum of the
: >car increases FOURfold.

:   Yes.

No, the energy increases by a factor of four, the momentum (m*v) only 
doubles.  Reaction time stays the same, reaction distances double, 
stopping times double, and stopping distances quadruple. (assuming constant 
deceleration).  Now if there is half as many things to hit, visible four 
times farther away, ... huh?

: >  From 50 to 75, while only a 50% increase in
: >speed, momentum increases 125%, which requires far longer breaking
: >distances and makes accidents far more dangerous.

See above, but the point is still valid, but if you include conditions as 
a factor in choosing speed, the point is muddled, which is the point.  

:   No; you had it right the first time -- it's kinetic energy, not momentum.

Yep.
--
James D. Landess
Sunnyvale, California


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