Re: Does speed affect weight?

Yes, speed effects weight due to the "ground effect".  At high speeds for 
a car (low speeds for an airplane), a force called "lift" is created.  A 
very good description and additional information on the ground effect can 
be found at the following link:
 htt
p://www.madsci.org/posts/archives/may2000/958682159.Ph.r.html

The lift raises the car off of the ground, reducing the contact of the 
tires.  Both steering and the propulsion rely on frictional contact 
between the tires and the road (the traction).  The spoiler creates a 
downward force, to counteract the lift, and improve the traction.

Chris Seaman
Sr. Staff Engineer
Alcoa Technical Center