The Efficiency (E) is an indicator of efficiency of any system, whether it be the car engine, the car or other mechanism. It shows how effectively this system uses the received energy. It is very easy to calculate efficiency.
Instruction
1. Most often efficiency is calculated from a ratio it is useful for the energy used by a system to all totally received energy in a certain period. It should be noted that efficiency has no certain units of measure. However, in the school program this size is measured as a percentage. This coefficient, proceeding from above the specified data, is calculated on a formula: η = (A/Q) of *100% where η (""this"") is it required efficiency, A - useful work of a system, Q - the summarized expenses of energy, A and Q are measured in Joules.
2. The way of calculation of efficiency stated above is not the only thing as useful work of a system (A) is calculated on a formula: A = Po-Pi, where Po - the brought to system energy from the outside, Pi - losses of energy during the work of a system. Having developed numerator of the formula stated above, it can be written down in the following look: η = ((Po-Pi)/Po) of *100%.
3. That calculation of efficiency was more clear and evident, it is possible to review examples. Example 1: Useful work of a system is equal to 75 J, the sum of the energy spent for its work is 100 J, it is required to find the efficiency of this system. Apply the very first formula to the solution of this task: η = 75/100 = 0.75 or 75%otvet: Efficiency of the offered system is 75%.
4. Example 2: The energy brought for operation of the engine makes 100 J, losses of energy during the operation of this engine of 25 J, it is necessary to calculate efficiency. For the solution of the offered task use the second formula of calculation of required coefficient: η = (100-25)/100 = 0.75 or 75%. Answers in both examples turned out identical, in the second case data of numerator were in more detail sorted.