The building and racing of a pinewood derby car can be a very difficult process.
Gravity is the main power source moving the car along the track.
Gravity pulls on an object at a rate of 32 feet per second per second. Gravity moves the car on the slope of the track, and ceases to move the car on the flat of the track. These two forces are components of the car's gravity force vector. Friction is the main force acting against the car. Friction is therefore the main cause of energy loss.