THE aquaplaning it is a phenomenon in which a vehicle, when passing over a layer of water, loses friction with the asphalt and slips. When this occurs, the driver loses control of the car and is unable to brake, which can lead to serious accidents.
According to Physics, what happens is a decrease in the friction force between the car and the ground. Dynamic friction force is calculated with the equation:
F = μd. N
Being:
F – Friction force;
μd – the coefficient of dynamic friction;
N – Normal Strength.
From the equation, it is possible to see a linear relationship between the friction force, the normal force and the dynamic friction coefficient. The normal force is the force that the asphalt exerts on the car and depends only on its weight. Therefore, the heavier the vehicle, the greater the normal force and the lesser the risk of losing contact with the ground.
The coefficient of dynamic friction μd ranges from 0.5 to 0.8 for dry asphalt, but this factor is also linked to asphalt conditions. For wet asphalt, this coefficient can have values from 0.25 to 0.75, depending on the amount of water. As we can see, these values are lower than when the asphalt is dry, therefore the friction force is lower, which increases the possibility of the car slipping.
Besides, there are other factors that influence this phenomenon, one of them is the speed of the car. The higher the speed, the less time the water has to move under the tires, which favors the occurrence of aquaplaning.
Tire characteristics and condition also deserve attention. Wide tires need to move more water, so the risk of slipping is greater. They must also be in good working condition, as the tires have grooves that drain water. As the tire is used, these grooves decrease and the capacity to drain water decreases as well. If this capacity is significantly reduced, it may favor the vehicle's skidding.
To avoid the aquaplaning, some small attitudes are essential for the driver: use tires in good condition, reduce speed when noticing large amount of water on the asphalt, do not brake abruptly or turn the steering wheel if you notice that you are losing contact with the ground. The ideal in these conditions is to stop accelerating the car and hold the steering wheel to ensure the wheels are straight. If the car has ABS brakes, which do not let the wheels lock when braking, they can be activated until the car regains its grip on the asphalt, allowing control over the vehicle.
By Mariane Mendes
Graduated in Physics