A vehicle going 40 mph can usually stop within how many feet?

When considering how quickly a vehicle can stop while traveling at 40 mph, it's important to take into account factors such as perception time, reaction time, and braking distance. Under typical conditions, a vehicle moving at 40 mph requires a combined total stopping distance, which includes both the distance traveled during the driver's perception and reaction times and the actual braking distance once the brakes are applied.

At 40 mph, the stopping distance can be estimated to be about 80 feet. This distance accounts for approximately 36 feet as the reaction distance and around 44 feet for braking distance on dry pavement. Therefore, the overall stopping distance, which reflects a safe estimate, tends toward 80 feet. This makes 80 feet the most reasonable and widely accepted answer for the stopping distance of a vehicle traveling at that speed.