| Re: Why can't car speedos be accurate? |
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Group: uk.transport · Group Profile
Author: MortimerMortimer Date: Sep 20, 2008 05:09
"Petert" googlemail.com> wrote in message
news:m1o9d4hir57o1ik14bbu1tamjde3dmg8il@4ax.com...> On Mon, 15 Sep 2008 05:29:39 -0700 (PDT), Boltar
> yahoo.co.uk> wrote:
>
> I suppose one reason is that the radius, or rather, the circumference
> of the wheels of cars/lorries etc aren't constant. It will change as
> the tyre wears down and as the pressure of the air inside it
> expands/contracts/leaks.
>
> Perhaps a different means of measuring the speed of a vehicle is
> needed - perhaps some sort of radar signal bounced off the road below
> the vehicle?
Or maybe laser light, using same technology as for laser mice. Or GPS
(assuming you can get satellite reception). May be overkill, though ;-)
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