A heat engine has a temperature of 1800 cap k Some of the heat from the engine flows to the surroundings, which are at a temperature of 160 cap k What is the approximate efficiency of the engine?

The maximum efficiency is given by 1 − (cold temperature ÷ hot temperature). Using 160 K for the surroundings and 1800 K for the engine gives 1 − 160/1800 ≈ 0.91, or about 91%. So the approximate efficiency is 91 percent.

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