Eric H.

As long as there is gravity keeping cars on the surface of the planet, four driven wheels will remain better than two. If cars travelled above the surface of the earth, however, traction of the sort now found in cars becomes irrelevant. <br>

Brian P.

When I hurt my back, I went to the Dr. for traction. Then there's the old frictional force - due to surface interactions between bodies in contact, usually a function of normal force, remember N = mgcos(theta)? and a multiplication factor usually Greek letter mu. Multiply both and get frictional force. "Traction" I'd like to see a definition. As for above the Earth's surface, I'd say there certainly is a drag force on an airplane. Doesn't the propeller blade have a "traction" on the surrounding air? Viscosity, ever hear of viscous heating? How's that different than your "Traction"? Even in zero G (an impossibility!) there's still viscosity. Does a boat have "traction"? Wow, check out Feinman's lectures....