Pinewood Derby Tips (Score 1)

My son usually won this race because I taught him about Newton's 2nd law of rotary motion; viz, angular acceleration equals applied torque divided by moment of inertia. Since the torque applied to the wheels is constant (it depends on the inclination angle of the track), their angular acceleration will be greater when their moment of inertia is smaller. So the fastest racers always have wheels with minimal moment of inertia. This means keep the majority of each wheel's total weight as close to the axle as you can. They could be spoked wheels with light weight rims and tires or disk wheels made of balsa glued to a pine hub.