A Rolling Discovery

I descended from the coat rack, slipped through the lower door threshold, and stepped into the cool morning air along the street. Beside the sidewalk curb lay a blue plastic roller skate left on its side. Its four urethane wheels caught my eye. I approached carefully, testing the rubber front stopper with my hand before bracing against the chassis. With a firm push of both arms, I spun the rear wheel. The miniature ball bearings inside whispered with a clean, low hum, rotating freely without friction. Motion, when properly balanced, requires very little force.