The ideal Carnot heat engine in one cycle received from the heater 8 * 10 ^ 4 J. What is the useful work done by the machine, if the refrigerator temperature is 20 ° C and heating to 300 ° C? What is the efficiency of the machine? How many times changes the pressure in an isothermal expansion of the gas, if the amount of the substance is 10 mole?

Detailed solution with a short recording conditions, laws and formulas used in the decision, the withdrawal of the calculation formula and the answer.
If you have any questions about the decision to write. I try to help.