Question 266: Thermodynamics & KTG

Question

An engine operating between the boiling and freezing points of water will have
A. efficiency more than 27%.
B. efficiency less than the efficiency of a Carnot engine operating between the same two temperatures.
C. efficiency equal to $$27 \%$$
D. efficiency less than $$27 \%$$
Choose the correct answer from the options given below:

Accepted Answer

To answer this question, we need to find the efficiency of a Carnot engine operating between the boiling and freezing points of water. The boiling point of water is 100ÃÂ°C (373 K) and the freezing point is 0ÃÂ°C (273 K). The efficiency of a Carnot engine is given by the formula:
Efficiency = $$1 - \frac{T_{cold}}{T_{hot}}$$
Plugging in the values for the boiling and freezing points of water:
Efficiency = $$1 - \frac{273}{373} = 1 - 0.732 = 0.268$$
So, the efficiency of a Carnot engine operating between these temperatures is approximately 26.8%.
Now, let's analyze the given options:
A. efficiency more than 27% - This is incorrect, as the Carnot efficiency is 26.8% and no engine can be more efficient than a Carnot engine.
B. efficiency less than the efficiency of a Carnot engine operating between the same two temperatures - This is correct, as real engines are less efficient than Carnot engines operating between the same temperatures.
C. efficiency equal to $$27 \%$$ - This is incorrect, as the Carnot efficiency is 26.8%, not 27%.
D. efficiency less than $$27 \%$$ - This is correct, as the efficiency is less than 27% (26.8%).
Thus, the correct answer is "B and D only."

Answer

B and C only

Answer

B and D only

Answer

B, C and D only

Answer

A and B only

Thermodynamics & KTG

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