Re: Tire marks on road

[SSHS KPHOX <kphox@MAIL.CCSD.K12.CO.US>]

PHYS-L@lists.nau.edu writes:
> At the beginning of the skid, the delta v between the
> locked tire and the road is greatest. Thus, I think
> the darkest area is at the start of the skid. Also, if
> you inspect the tire tracks of a car that has "peeled
> out" from a standing start, the tracks are darkest at
> the start of the "peel", not at the end. Again,
> greater delta v seems to be associated with darkness.
> John Barrere

I don't entirely agree with this. With the "peel out" I would think the
the lower the v  (not delta v) that more rubber/distance would be
deposited and thus (as you said) it would be darker at the start. Spinning
out yields hot sticky tires. At the end of the skid the hotter tires would
be "painting" more slowly leaving the end of the skid darker.

Just a guess; now we need to experiment with someone else's car.

Ken Fox

This posting is the position of the writer, not that of SUNY-BSC, NAU or the AAPT.