> List,
>
> Education can be a dangerous thing. Next quarter at the
> VoTech school, I'm taking suspensions and front ends.
> Reading ahead I came across a paragraph that discussed
> tire speed dynamics> It said that at 55 mph, the portion
> of the tire directly fore and aft of the axle was
> traveling at 55mph,
No. 78 MPH is my guess. Up at a 45-degree angle at the
back and down at a 45-degree angle the front.
Now, if the statement of the question is "ignoring vertical
motion, what is the instantaneous velocity in a horizontal
direction", then, yes, the points at the front and back
edges of the tire are indeed traveling 55 MPH.
> the portion of the tire at the very
> top was traveling 110mph
True.
> and the portion of the tire at
> the very bottom was traveling 0mph.
True.
All of the above are considering the earth as the frame of
reference. I can't imagine what the practical value would
be in knowing this. I'm not a engineering student, so when
your prof comes to this part, maybe you can explain it to
us.
The average of all the instantaneous velocities will be 55
MPH whether or not you are ignoring the vertical component
in all cases.
To figure the forces on the tire, I would expect that you
would rather know the velocities using the car as the frame
of reference.
For figuring suspension forces for lateral acceleration
whilst cornering, you pretty-much ignore the rotation of the
wheel. The centripetal force (which DOES exist when you are
considering the car as the frame of reference) acts on the
tire patch and all the suspension forces are figured from
there.
Phil Ethier West Side Saint Paul Minnesota USA
1962 TR4 CT2846L, 1992 Saturn SL2, 1993 Suburban, 1994 Miata
C package
pethier@isd.net
http://forum.mnautox.com/forums/
http://www.flickr.com/photos/pethier
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