35.55. Do you agree that when the speed is doubled, the braking distance increases approximately fourfold:
UAЧи погоджуєтесь Ви з тим, що при збільшенні швидкості у два рази, гальмовий шлях збільшується приблизно у чотири рази:
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This exam question from the Traffic Rules of Ukraine concerns road safety and the actual ability of a vehicle to stop in time. It highlights a key principle: as speed increases, the demands for controlling the situation on the road, as well as for distance and driver attentiveness, increase sharply. For the theoretical exam, it is important to understand that the danger at high speed lies not only in having less time to react, but also in the significantly greater distance required for a complete stop.
The question tests Section 12 of the Traffic Rules, specifically the requirements of points 12.1 and 12.3 regarding the choice of safe speed and the obligation to immediately reduce speed up to a stop in case of danger, as well as being related to Section 13 (point 13.1) on safe distance. The correct statement is based on the physics of braking: the braking distance increases approximately in proportion to the square of the speed, so when the speed is doubled, it increases by about four times under the same conditions (surface, tires, brakes, load). This is exactly what the correct answer confirms, while denial contradicts the typical relationship and can lead to dangerously underestimating the required distance.
The practical conclusion for the driver is simple: if you increase your speed, you need to significantly increase the space ahead and be prepared for a longer stop, especially on wet roads, with worn tires, or poor traction. This knowledge is directly related to everyday safety and helps to correctly apply the traffic rules, choosing such a speed and distance that within the visible range you can realistically react and stop without risking other road users.
Clause 12.1 (Section 12 "Speed of Movement")
When choosing a safe speed within the established limits, the driver must take into account the road situation, as well as the characteristics of the cargo being transported and the condition of the vehicle, in order to be able to constantly control its movement and drive it safely.
This clause checks the understanding that as speed increases, the requirements for the ability to control and stop safely increase sharply, particularly due to the increase in braking distance.
Clause 12.3 (Section 12 "Speed of Movement")
If a danger to traffic or an obstacle that the driver can objectively detect arises, he must immediately take measures to reduce speed up to stopping the vehicle or safely bypassing the obstacle for other road users.
This clause is related to the practical consequence of increased braking distance at higher speeds: in order to be able to stop "up to a complete stop" in time, the speed must be chosen taking into account the actual stopping distance.
Clause 13.1 (Section 13 "Distance, Interval")
Depending on the speed, road situation, characteristics of the cargo being transported, and the condition of the vehicle, the driver must maintain a safe distance and a safe interval.
This clause checks the understanding that as speed increases, it is necessary to significantly increase the distance, because the braking distance increases (including according to the quadratic dependence "twice the speed — approximately four times the braking distance").
Clause 2.3 (subclause "b") (Section 2 "Duties and Rights of Drivers of Motor Vehicles")
The driver is obliged to: be attentive, monitor the road situation, respond appropriately to its changes, monitor the correct placement and securing of cargo, the technical condition of the vehicle, and not be distracted from driving this vehicle on the road.
Knowledge of how braking distance increases with speed is part of "appropriate response" to changes in the road situation and the correct choice of speed/distance.
Therefore, the correct answer is "Yes.", given that according to the Traffic Rules, the driver is obliged to choose a safe speed and distance taking into account the ability to timely reduce speed up to a stop, and as speed increases, the braking distance increases significantly (approximately proportional to the square of the speed).
When braking, a car must dissipate its kinetic energy. This energy depends on speed not directly, but by the square: the faster you go, the much more energy needs to be “removed” by the brakes and the tires’ grip on the road. Therefore, increasing speed results in a disproportionately large increase in braking distance.
In practice, this means the following: if the speed doubles, the kinetic energy increases by approximately four times, and to dissipate it under the same conditions (road, tires, brakes, load), you need about four times the distance. That is why the relationship between speed and braking distance is quadratic, not linear.
This aligns with the Traffic Rules requirements for safe speed and distance: the driver must drive at such a speed as to be able to constantly control the movement and stop the vehicle within the visible area and safely for others. If the driver doubles the speed, they must understand that the stopping distance must be much greater; otherwise, the risk of not stopping in time increases sharply.
For illustration: if under certain conditions at 50 km/h the braking distance is about 25 m, then at 100 km/h under the same conditions it will be about 100 m. That is, doubling the speed results in approximately a fourfold increase in braking distance.
Thus, the correct answer is "Yes.", because the braking distance increases approximately in proportion to the square of the speed, and when the speed doubles, it increases by about four times.