Neither the tire nor the roadway are completely smooth surfaces in most
cases. Given the tread pattern of the tire and the roughness of the
roadway, some seepage would be expected over time.
An empirical test would establish how long it would take for appreciable
seepage.
Mark
-----Original Message-----
From: kyle forinash [mailto:kforinas@IUS.EDU]
Sent: Thursday, May 24, 2001 6:51 AM
To: PHYS-L@lists.nau.edu
Subject: gruesome question
Sometimes you get asked weird questions, here is one I hope someone
can give me some insight to (I suppose I could get called to testify
on this).
The county prosecutor's office called me with the following question.
A car is sitting on an asphalt roadway. Blood is found around and
UNDER a tire. But they don't think the car drove over the blood (no
tracks). Is normal asphalt porous enough for blood to seep under the
tire without moving the tire?
I'm thinking probably yes (asphalt starts out as separate particles
so capillary action between the grains could do the job), but is
there anyway to establish that for sure? How porous is asphalt?