Rus Articles Journal

# Percent on a road sign - the important prevention?

Quiet early morning. It is a high time to do good. What can be better than a gift to our mothers - some modest bouquet. But a bouquet not of flowers, and some necessary in the woman`s life - the motorist of knowledge!

you already paid attention to the warning road signs with the black triangle symbolizing descent or rise and the number of percent designating the steepness of this descent (or rise)? And, perhaps, asked themselves a question - and, for example, 12% are how many? And why not to designate the steepness of a bias in degrees?

On these signs the inclination tangent of angle expressed as a percentage is designated.

There now, your smile withered as if, having developed a package of a gift, you found in it weighty volume of Dostoyevsky. And already in a few minutes you will easy operate with the concept “tangent“, and at the same time “sine“ and “cosine“, being surprised to the fact that till today they forced you to strain.

So, lean a ski stick a corner against a wall opposite to a bright lamp. You will see two shadows - one on a wall, another on a floor. Teachers, that to tease you, called these shadows projections. Respectively, on the vertical and horizontal planes. That shadow that on a wall, “sine“, that is called that on a floor - “cosine“.

The closer to a wall you will move up a stick bottom, the “cosine“ will be shorter. On the contrary, removing a stick bottom from a wall, you will see that “sine“ becomes less, and “cosine“ - is more. The sine relation to a cosine is called a tangent.

If you establish a stick at an angle of 45 degrees from a floor, the sine and a cosine will be absolutely identical. In that case the tangent will be equal to 1. Or, as your teachers spoke, the tangent of 45 degrees is equal to 1.

If we look sideways at the road, in that place where it has a bias, then we will see that the corner of this bias is in limits of 8 degrees from the horizon. Rise height, or “sine“ is, much less, than the road projection length to the horizontal plane - “cosine“. Having divided rise height into length of a horizontal projection, we will find out that the tangent of angle of such bias does not exceed 0,12.

It is convenient to express it as a percentage - for example, 12%. In that case the tangent of angle of 45 degrees is equal to 100%.

Now you already safely can use this information. So, having passed 1 kilometer on the road with a bias of 12%, you will rise (or go down) by 120 meters. (At such small corners of a bias the equal length of the road can consider length of a horizontal projection of the road).

Out of curiosity you can transfer a bias corner back to degrees by means of the calculator on the cell phone, having adjusted it on the “scientific“ mode, for example: TAN - 1 (0,12) =7 degrees. In some calculators: ATAN(0,12)=7.

However, for motorists the main thing not it. I hope, you already read my article about coupling coefficient.

And so, it appears, a tangent of angle of an inclination is equal to coupling coefficient .

For example, the car standing on the dry asphalted bias with coefficient of coupling 0,7 will begin to slip down if the inclination tangent of angle at the same time is equal to 70% (It is a bias about 35 degrees, hardly you will sometime meet such.)

But, except roads, there are small streets of the old cities, especially seaside, with the tilt angles significantly exceeding various standards. So, at the movement during wet weather down the asphalted bias by the steepness of 20% efficiency of braking falls half.

And very often you should move on wet ice with coefficient of coupling 0,1 and less. And it means that you have to trace attentively warning road signs with a black triangle and figures inside. They are established when the tangent of angle of a bias approaches 10%. If you neglect these signs and stop on rise, then at best - you will not be able to move a little. And if slow down on descent … But I am convinced by

that now nothing of that kind happens to you. And with all the heart I hope that today though a little helped you, dear mothers - our most responsible and favourite part of mankind.