How to know the efficiency?
Coefficient of efficiency (EFFICIENCY) is onefrom the most important characteristics of machines, mechanisms, devices, systems, where the processes associated with the transfer or transformation of energy occur. Therefore, before using a device, its efficiency is calculated to assess the effectiveness of its possible use. We will talk about how to know the efficiency, by what formula this parameter is calculated and how it is determined by science.
How to know the efficiency? Coefficient is the ratio of useful work to full work. For convenience, the result is multiplied by 100 and the answer is obtained in percent.
The formula for calculating the efficiency, which is usually denoted by the Greek letter η ("this"), is written as follows:
- η = (A useful / A complete) * 100%, where A is the work.
For example, to lift a load to a certain height, it is necessary to perform a useful work A useful = 5000 J. To raise the same load with an elevator to the same height, you need to complete the work A complete = 8,000 J.
Thus, the efficiency of the elevator is:
- η = (A useful / A complete) * 100% = (5000 J / 8000 J) * 100% = 62.5%
Also, efficiency is sometimes defined as the ratio of the power given by the mechanism to the power supplied to it or as the ratio of the useful energy to all the energy received by the system.
Since part of the total work of the machine is spent onthe heating of their parts, the struggle with friction and resistance forces and other needs, work at the exit or useful work is always less than full work. Thus, the efficiency can not be more than 100%.
For example, the efficiency of the internal combustion engine is 20-40%, the steam turbine 30%, the electric motor up to 98%.
Many people are interested in knowing their efficiency, that is, the devices they use. Often, this does not need to carry out calculations, but rather look into the technical passport of the mechanism.
Sometimes the notion of efficiency is used to describethe effectiveness of the work of the person. But how do you know your efficiency? Of course, we are not talking here about numbers, but only about such values as "high" or "low." To do this, compare the final result of any work with the efforts expended, compare the results of comparison with similar activities of other people or yourself at another time.
