Motorists are accustomed to measuring the power of their own "iron horse" in units that are called "horsepower." This parameter has been known since the last century, however, it applies even to ultra-modern sports cars, which with a great stretch can be equated to any kind of “herds”.
This unit is not derived from basic calculations in the SI, and its value in different countries can be calculated differently. A more accurate indicator of power can serve as a watt, which is equally calculated anywhere in the world. Consider how to convert kilowatts to horsepower, as well as why this should be done.
- 1 The story of the emergence of "horsepower"
- 2 Measurements for the Russian Federation
- 3 International measurement of hp
- 4 Conclusion
The story of the emergence of "horsepower"
At the beginning of the nineteenth century, the inventor and scientist from Scotland James Watt tried to promote the introduction of the steam engine instead of using horses. One of the first buyers of this mechanism turned out to be a brewer, in which animals worked as a tractive effort to rotate a water pump. Comparing the force that developed from animal thrust with the power of the artificial mechanism, the scientist calculated the reference value.
The estimated values that James Watt took as baseline were a barrel of water weighing 380 pounds or 1 barrel (172.4 kg), an eight-hour working day, two horses weighing 500 kg each, capable of producing approximately 15% of the useful work of their mass. During this time, animals walked 20 miles (28.8 km) at a speed of 2 miles / hour (3.6 km / h). In such calculations, the traditional English horsepower (hp) should be calculated by the formula:
0.5 barrel * 2 mph = 1 hp
The barrel in this case does not act as a unit of mass, but as a unit of force.
Only after nearly a century, at the end of the 19th century, the British Scientific Association introduced a new unit of power, dedicating it to the Scottish scientist - watt (W or W). This parameter was calculated in generally accepted SI units.See also: What should be in the first-aid kit of the car
Measurements for the Russian Federation
In order to bring this parameter to a single standard, in our country it was adopted the designation of the conditional “metric horsepower”. Therefore, the conversion of kilowatts to horsepower in Russia is based on the value of:
1 hp = 735.49875 W
In mathematical calculations, this parameter is tried not to be applied, but it is relied upon when calculating the cost of compulsory insurance of CTP or transport tax. This is due to the fact that in the characteristics of their products auto enterprises often use not watts but hp, although in the international system of units SI installed wattas a power parameter.
International metrology organizations recommend switching in the designation of all vehicle characteristics to the SI classification.
International measurement of hp
For most countries of the European continent, the parameter is adopted:
1 hp = 75 kgf · m / s
Finding out how many kilowatts in horsepower, we get that such power corresponds to lifting a weight of 75 kg at a speed of 1 m / s with a normal value of the acceleration of free fall. Translated into watts, we get 735.49875 W, which corresponds to Russian standards. Although hp and is a non-system unit of measurement.
The United States, along with Great Britain, uses the parameter they have adjusted. In their calculus:
1 hp = 745,69988145 W
In order to distinguish in which system the value of horsepower is indicated, sometimes a measuring unit of a country is put:
- German - PS;
- French - ch;
- English - hp;
- Dutch - pk.
For the inverse calculation of kilowatts and metric (Russian) values of hp You can use the formula:
1 kW = 1.3596 l. with.
For the United States also applies the value of "electric horsepower." Its parameter is calculated by the formula:
1 Boiler horsepower =746 Вт
This value is used in industry and energy.
Concepts that non-system units are a thing of the past. Increasingly, car power values are written in watts. At the same time, there are sites where it is possible to calculate the forward or reverse value online in any unit. The Russian unit hp is usually taken as a formula.See also: How to get rid of fumes