Why there are accidents? Radius of turn is
Turn - one of the most dangerous sites of the road. Also it is terrible the uncertainty. To win against this fear, learn more about turn and first of all - about its radius!
Each road has the plan . The plan is position of the road on the district. If you flew by plane, then roads looked thin lines with the rounded-off breaks. These are turns. If to look narrowly, then all turns are parts of circles of various radius. At those turns that more abruptly, radius is less and vice versa. It is clear, that the same turn can be constructed with various radius (see drawing).
In the childhood, riding a roundabout, you learned that at the movement on a circle any body is affected by force directed from the center of this circle. This force is called centrifugal . It rejected from a vertical a roundabout chain with the seat attached to it in which you sat.
Centrifugal force affects also the car moving on a turn circle, dragging away it from the center of this circle. Every time, approaching the next turn, you, without noticing that, quickly in mind and it is, as a rule, faultless, you solve the same problem.
We will assume, it is raining. You approach by the car weighing 1000 kg with a speed of 108 km/h turn with a radius of 50 meters. Whether it is possible, without reducing speed, to pass turn?
From the previous article you already know that the coefficient of coupling of wet asphalt is equal to 0,4.
Having increased force with which your car is attracted to the road, by coupling coefficient, we will find force with which the car will begin to move sideways from a movement trajectory:
10000 x 0,4 = 4000 N
Having remembered occupations in driving school, we will find centrifugal force, having increased the mass of the car by its speed in a square and having divided all this into turn radius.
At first we will express car speed in meters per second:
108 x 1000: 3600 = 30 m/s
we substitute the available values in a formula Now:
Centrifugal force is equal to 1000 kg x (30 m/s x 30 m/s): 50 m = 18000 N
18000 N are much more than 4000 N! This force more than is sufficient in order that your car not just moved, and took off from turn far for a roadside!
What to do, in horror you think! Probably, it is necessary to reduce speed to such value that centrifugal force could not shift the car from a trajectory of its movement, that is did not exceed 4000 N
we Will hurry to find this speed, the car inevitably approaches turn! This speed is equal to a square root from work of coefficient of coupling on the radius of turn and on acceleration of gravity.
Speed is equal in a square 0,4 x 50 m x 10 m / s2 = 200, the square root from 200 is equal to about 14 m/s.
We will transfer meters per second to kilometers per hour:
14: 1000 x 3600 = 50 km/h
of Uf, were in time! Our brain does all calculations imperceptibly for us. But not without consequences for an organism. At approach to abrupt turn and during the movement on it pulse sharply becomes frequent, arterial pressure increases, paints grow dull - sight begins to pass it from color in is black - the white mode, and even from the continuous mode - in faltering. All resources of an organism go to the help to a brain. Help also you to it!
Stop talk, ask the passenger not to ask questions to the driver at approach to turn or to the intersection. Have a look in a rear-view mirror and begin in good time, to reduce speed before entry into turn and to brake. Let`s a brain work in comfortable conditions.
Alas, the quantity of mistakes increases in inverse proportion to turn radius. Fortunately, wise road builders for us already solved all problems. They built all turns depending on category of roads.