Wagon wheel effect - questions and answers. If you have a question about this topic, please click on the "New Question" button. If you wouldn't like to miss any new question in this topic, please subscribe.
We’ve all seen it in movies or old TV westerns—as the stagecoach (or train) picks up speed, its fast-moving wheels appear to switch direction, slowly turning backward. We also occasionally see the phenomenon in real life, with spinning car tires and whirling ceiling fans. Scientists call it the Wagon-Wheel Effect. What causes the “backward” effect?