What is the mnemonic for judging car distance using side mirrors?
2 Answers
The mnemonic for judging car distance using side mirrors: The smaller the rear vehicle appears, the safer it is; When the rear vehicle occupies 1/3 of the mirror, the distance is about 10 meters; When occupying 1/2 of the mirror, the distance is about 7 meters - safe for turning; When the rear vehicle fills the entire mirror, the distance is about 3 meters - not suitable for turning. Below is an introduction to rearview mirrors: 1. Structure principle of rearview mirrors: Rearview mirrors involve a field of vision issue, referring to the range that the mirror surface can reflect. The industry proposes three elements of vision: the distance between the driver's eyes and the rearview mirror; the size of the rearview mirror; and the curvature radius of the mirror surface. These three elements are interrelated - with equal distance and size, a smaller curvature radius provides a wider reflected field. With equal curvature radius, a larger mirror size provides a wider reflected field. 2. Reflectivity index of rearview mirrors: Rearview mirrors also have a reflectivity index. Higher reflectivity means clearer reflected images, which depends on the reflective coating material on the mirror's inner surface.
Having driven for decades, I know the mantra by heart: for the right side mirror to gauge the distance of the car behind, when the car's image occupies about half the mirror's width, it's roughly 4 to 5 meters away. The left side mirror follows the same principle, but with a wider field of view, making judgment easier. The key is this mantra helps avoid rear-end collisions—the smaller the car's image, the farther it is; the larger, the closer. Take action promptly; don't just stare. Beginners should practice more—find a parking spot, observe the size of parked cars' images, and get a feel for real distances. Also, check if the mirrors are adjusted correctly; if they're too tilted or too high, their effectiveness drops significantly. Safe driving isn't something to take lightly, especially at night or in rainy weather.
