"John Rumm" wrote in message
...
dennis@home wrote:

Say 70 mph with a spacing of 70m (much less than the 315 ft in the
highway code but it will do.

The highway code shows a minimum car to car distance of 2 seconds, which
at 70mph equates to 62m at or just over 200 feet. At 100mph that equates
to 88m.

You know you really ought to have a look at the book if you are going to
quote it, rather than just making up stuff.

The book is written for a maximum speed of 70 mph.
If you want to set the limmits to 100mph then it will have to be changed.
Do think about it before quoting what would be out of date sources.


So as the energy is V x V we need to extend that distance by 2 times as
the energy between 70 and 100 is doubled.

Not really. The kinetic energy is proportional to v^2 not equal to it (you
need to include mass into the equation).

No I don't you aren't going to produce new half as light cars to drive at
100mph you are talking about the same ones.

The drag is proportional to v^3. So there is a massive increase in
retardation available at 100mph that will kick in the moment you remove
the motive force. So even if you wish to set your car spacing based on KE
values, you can get them closer that those number alone would suggest, and
them still be within stopping distances.

Still much of this is pointless hot air anyway, the vast majority of
accidents occur on 30mph roads, so you are focussing on the wrong problem
to solve in the first place.

Its not me that keeps bringing up motorways and 100+ mph driving.