More KE less Friction (f): f=mu*F(Force Perpendicular)

[Jewel]

Misconceptions and flaws of thought are the true enemies to speed.

One paragraph of philosophy. In my opinion we need to have a little courage to learn because we must discover and then remove our misconceptions and flaws of thought, which involves revealing; we must reveal our uncertainties, we must reveal our lack of knowledge and expose ourselves to the bright light of truth. Physics is a nice bright light because we can discover by careful testing how accurate ideas really are. So a word to the scouts looking to do better, courage and learning go well together add a little dedication and you are on your way to victory.

Friction is a slippery topic, I felt like surface area was an important factor to minimize. It seems that this is not the case. I tried to reduce friction in my car by adding a .050 steel ball bearing below each axel. Was this the best way to reduce friction in my car?

The rules at my race do not allow the hub to be relieved rounded or coned, the hub face must be flat and square to hub ID. So after reading and not understanding the book LBW I thought that surface area must be minimized. So my solution was the ball bearing. Sounds good, but what you really need to do is reduce the radius of the lever arm that is contacting the wheel to minimize the braking torque. A better solution for me because the rules I follow allow that car body to be changed would be to put a cone shaped feature around the axel on the car body itself. This would allow the hub to touch at a minimum radius, which would decrease the torque and thus the force of friction acting on the wheel.

Mu and the perpendicular force between bodies that are either rolling or sliding past one another denote friction in physics. More technical folks I hope will add some comments so that we are all clear on how this works.

Some general questions. How do we understand mu? How do we understand rolling vs. sliding friction? Where are all the points of friction in your Pinecar?

Ultimately we want more KE (Kinetic Energy) and less frictional losses.

[Stan Pope]

The idea of a polished steel shot (ball bearing) embedded in the side of the car to be the contact point for the wheel hub is not inherently a bad idea. The fact that it contacted around midway out on the flat hub surface was the problem.

If the steel shot is relocated so that it contacts the innermost area fo the hub face, then you're "in business." In so doing, I'd suggest below the axle as probably the best location.

In my district, the cone around the axle would probably be rejected by the rules (as a "washer", perhaps), but the steel shot embedded in the side of the car would probably be accepted.

I thought i gave a game try at getting that braking torque concept across ... sorry that it took two tries.