During the operation of the heat engine, for a certain time, the working heat received from the heater

During the operation of the heat engine, for a certain time, the working heat received from the heater an amount of heat equal to 2.0 MJ, and gave the refrigerator 1.5 MJ. Calculate the efficiency of the machine.

Qн = 2.0 MJ = 2 * 10 ^ 6 Joules – the amount of heat received by the heat engine from the heater;

Qx = 1.5 MJ = 1.5 * 10 ^ 6 Joules – the amount of heat given by the heat engine to the refrigerator.

It is required to determine n (%) – the efficiency of the heat engine.

Let’s define the useful work performed by the heat engine:

A = Qn – Qx = 2 * 10 ^ 6 – 1.5 * 10 ^ 6 = 0.5 * 10 ^ 6 Joules.

Then, in order to determine the efficiency of a heat engine, it is necessary to use the following formula:

n = (A / Qн) * 100;

n = (0.5 * 10 ^ 6 / (2 * 10 ^ 6)) * 100;

n = (0.5 / 2) * 100 = 0.25 * 100 = 25%.

Answer: the efficiency of the heat engine is 25%.