The speed of the vehicle is constantly changing during travel. Determining what speed the car had at one point or another on the way is very often done by both the motorists themselves and the competent authorities. Moreover, there are a lot of ways to find out the speed of a car.
Instructions
Step 1
The easiest way to determine the speed of a car is familiar to everyone since school. To do this, you need to record the number of kilometers that you traveled and the time during which you covered this distance. The speed of the car is calculated according to the formula: distance (km) divided by time (hours). This will give you the desired number.
Step 2
The second option is used when the car stopped abruptly, but no one took basic measurements, such as the time and distance. In this case, the vehicle speed is calculated from its braking distance. There is even a formula for such calculations. But it can only be used if there is a trace left on the road during braking.
Step 3
So, the formula is as follows: the initial speed of the car is 0.5 x the braking rise time (m / s) x, the steady-state deceleration of the car when braking (m / s²) + the root of the stopping distance (m) x, the steady-state deceleration of the car at braking (m / s²). The value called "steady-state deceleration of a car when braking" is fixed and depends only on what kind of asphalt took place. In the case of a dry road, substitute the number 6, 8 in the formula - it is spelled out in the GOST used for calculations. For wet asphalt, this value will be 5.
Step 4
You can also determine the speed along the braking distance using one more formula. It looks like this: S = Ke x V x V / (254 x Fs). The following values must be substituted into this formula: braking coefficient (Ke) - for cars, this value is usually taken as 1, speed at the beginning of braking (V), coefficient of adhesion to the road (Fs) - for different weather conditions, its value is determined: dry asphalt - 0, 7, wet road - 0, 4, packed snow - 0, 2, icy track - 0, 1.
Step 5
You can determine the speed of the vehicle in a particular gear. To do this, you need the following values: the number of revolutions of the crankshaft (Nc), the dynamic radius of the wheel (R), the gear ratio of the gear (in), the gear ratio of the main pair (irn), the initial speed of the vehicle (Va). Calculate the speed using the formula: Va = Nc x 60 x 2Pi x R / (1000 x in x irn).
