How many meters does it take to brake from 120 km/h?
2 Answers
At a speed of 120 km/h, an emergency brake requires approximately 45 meters to come to a complete stop. Here is a related introduction about emergency braking in cars: The main hazards of frequent emergency braking: Primarily affects tire lifespan, increases wear; reduces engine lifespan; decreases clutch system lifespan; increases fuel consumption; shortens brake pad and disc lifespan; accelerates aging of brake calipers and master cylinders. Countermeasures: If only the brake pedal is pressed, the braking force needs to overcome two aspects: the vehicle's kinetic energy and the engine's traction force. However, if both the brake pedal and clutch pedal are pressed simultaneously, the torque output from the engine's output shaft is disconnected from the driveshaft during braking. In this case, the braking force only needs to overcome the vehicle's kinetic energy without dealing with the engine's traction force, resulting in a shorter braking distance.
When I first started driving on the highway, I was also curious about this—how much distance is actually needed to stop when going 120 km/h. I remember testing it last year in my old sedan on a dry road. I prepared in advance and slammed the brakes all the way down. It felt like the car slid forward quite a distance before coming to a complete stop, and my phone app measured it at around 80 meters. But there's really no fixed number—better cars stop in shorter distances. For example, newer cars with ABS systems might only need about 60 meters. Rainy conditions definitely increase the distance. Once, driving at the same speed on a rainy night, I estimated it took over 100 meters to come to a full stop. The key factors are tire grip and road surface conditions. For safety, I usually try to maintain a following distance of at least twice the speed on the speedometer, giving myself some margin.
