What is the fastest possible slot car one can build? What are the limiting factors?
Obviously, we have to require that the motor is aboard the car and that it's propelled by the wheels (we don't want a particle collider or a rocket), and we want a closed track and go many rounds (we don't want a drag racer).
I guess we would build a large looping, but at which speed will it break from centrifugal force? How much energy can we pump into the car before the track melts? Can we cool the whole race track down to use superconductors? Do we want to evacuate the whole track to avoid sound barrier effects or do we need air for something (cooling? aerodynamic control surfaces on the car?)?