You wouldn't think that a four-wheeled car would go faster if one of its wheels didn't touch the ground. Or if its axles were bent. Or if it was designed to grind against a wall. You would be wrong, and here's the science to prove it.
Our old friend Mark Rober -- former NASA JPL engineer -- has put together an exhaustive video on how to make the very best Pinewood Derby car. Full disclosure, I'd never heard of Pinewood Derbies -- wherein Cub Scouts and Boy Scots make little cars and race them down a straight track -- before this, but apparently they're quite popular. Over 100 million cars have been made over the last sixty years.
As you might imagine, people really nerd out over how to make the best one, and a lot of it could make your eyes cross if you don't have a degree in physics. Mark breaks it down into extremely easy-to-grasp terms. He also demonstrates an illegal derby car that goes 40 miles per hour. Anyway, if you've got a kid in Scouts -- or are clinging to memories of getting smoked -- think of this as your ultimate cheat-sheet. [Mark Rober]