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How can you measure the braking distance of a car with a good reliability in normal conditions?

From classical physics, we can assume that the braking distance can be found by determining the work needed to dissipate the vehicle kinetic energy.

After some work, we can reach the following formula:

[tex]d=vt + \frac{v^2}{2gμ}[/tex]

with the first part being the distance traveled before reaction time (which I will ignore)

assuming that μ=0.7, g=9.81m/s2 and v=100km/h

I've done some research and found 0.7 for μ

With those values, the braking distance is about 56 meters, far different from a (first reference car I've found) Nissan GTR (R35 - 2011) 32.75 meters braking distance.

Ok, if we find another value for μ such as 1.0 (hi-performance tire / hpwizard.com) which is close to a treadwear friction coef from a Dunlop 7010 tires (TW=240)

the braking distance become about 39 meters, which is more plausible but not the accuracy I want.

My first is: the classic physics formulas can return the approximated braking distance?

I mean, the formula does not take into account the drag force / the car weight distribution / the dive effect when the car brakes / maybe μ varies from tire temp, speed / rolling resistance / etc...

These are the values we can return or there are some others important values we need to take into account?

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# Automotive Car braking distance

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