Braking of a car

Ever wondered how a car stops?
The process of braking of a car can be broken down into three steps:
  1. Reaction
  2. Applying the brakes
  3. Deceleration

First of all, the human, or the person driving/controlling the vehicle assesses the situation and decides to stop the vehicle.

Next, the person applies the brake pedal, or engages the braking system of the vehicle.

Further, the physical forces work and decelerate the car until it stops.

Total stopping distance consists of three components:

  1. Reaction Distance. First. Suppose the reaction time is 1.5 seconds. This means that the car will travel 1.5 x80.67 or 120.9 feet before the brakes are even applied.
  2. Brake Engagement Distance. Most reaction time studies consider the response completed at the moment the foot touches the brake pedal. However, brakes do not engage instantaneously. There is an additional time required for the pedal to depress and for the brakes to engage. This is variable and difficult to summarize in a single number because it depends on urgency and braking style. In an emergency, a reasonable estimate is .3 second, adding another 24.2 feet.
  3. Physical Force Distance. Once the brakes engage, the stopping distance is determined by physical forces (D=S²/(30*f) where S is mph) as 134.4 feet.

Total Stopping Distance = 120.9 ft + 24.2 ft + 134.4 ft = 279.5 ft

(Source: Marc Green’s article on Human Factors)

An interactive visualization for the scenario can be seen by clicking on the below link.


Thanks for reading the post 🙂


3 thoughts on “Braking of a car

  1. Hey,
    Insightful, as to how the reaction time plays a role.
    One question, can you explain the physical braking phase a little bit more in detail and how you worked out that number?


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