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About the Pinewood Derby Theory

The Pinewood Derby is a miniature car race facilitated by the Boy Scouts of America. The specific rules of each race are decided by the troop running the Derby, although there are loose universal standards set forth by the Boy Scouts of America. There are four main theories based on physics to build a faster car: weight theory, concentration of mass or weight-placement Theory, axle-polishing theory and rail-riding theory.

Pinewood Derby
- According to the Boy Scouts of America website, Pinewood Derby is an event organized by Cub Scouts throughout the year. Each Cub Scout and an adult helper build a wooden car and race it against other cars on race day. Each Cub Scout pack decides its own rules for its Pinewood Derby race, including the exact height and weight requirements for each car.
Weight Theory
- The maximum weight set forth by the Boy Scouts of America in any Pinewood Derby is 5 ounces. To overcome friction, the car should be as close to this weight as possible. To make the car heavier, less pinewood should be used in the construction of the car to allow the use of more lead or tungsten weight.
Concentration of Mass
- The area of the derby track where the sloped track becomes a flat track is called the transfer zone. According to the concentration of mass theory, it is critical to place the car's center of mass toward the rear of the car to maximize gravity's push as long as possible in the transfer zone.
Axle Polishing
- Sandpaper is used to smooth and sand the axle parts that come in direct contact with the wheel of the car. The nail near the head of the car should also be polished, as well as the head itself. Once each part of all axles have been sanded, they are smoothed with pumice powder and a dampened rag. This cuts down on drag from friction and allows the wheels to spin at optimum speed.
Rail-Riding
- According to the ABC Pinewood Car Company, this method is an easy way to build a smooth-riding car with or without a test track. When building the car, mark the axle at .350 inches from the head. Then put a dot at 12 o'clock on the head. Install the axle at .350 using a hammer to lightly tap to achieve a slight bend.
  
  Install the rear axles with the 12:00 dot up. Finally, the front head of the car should narrow 1/16 of an inch in relation to the rear wheel on the same side. Using this theory, only the dominant front wheel makes contact with the guide rail. This causes the back wheels to never touch the guide rail, which reduces drag caused by friction.

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