The heat engine has an efficiency of 40%. in one cycle of operation, it gives the refrigerator an amount

The heat engine has an efficiency of 40%. in one cycle of operation, it gives the refrigerator an amount of heat equal to 600 J. How much heat does the machine receive from the heater?

Heat engine efficiency:

η = ((Q1 – Q2) / Q1) * 100%, where η is the efficiency (η = 40% = 0.4), Q1 is the amount of heat that the heat machine received from the heater, Q2 is the amount of heat that the heat machine to the refrigerator (Q2 = 600 J).

Let us express and calculate the amount of heat received from the heater:

η * Q1 = Q1 – Q2.

Q2 = Q1 – η * Q1.

Q2 = Q1 (1 – η).

Q1 = Q2 / (1 – η) = 600 / (1 – 0.4) = 600 / 0.6 = 1000 J = 1 kJ.

Answer: The heat engine receives 1 kJ of heat from the heater.