In an engine operating in the Otto cycle, the final volume of the fuel-air mixture is one sixth the initial volume. Assume γ = 1.4. The maximum theoretical efficiency of this cycle, in per cent, is
A) 17.
B) 49.
C) 51.
D) 56.
E) 83.

Question

Quizplus · Accepted Answer

The efficiency of the Otto cycle is given by:

η = 1 - (1/r)^(γ-1)

where r is the compression ratio defined as the ratio of the initial volume (Vi) to the final volume (Vf):

r = Vi/Vf = 6

Substituting this into the efficiency equation and using γ = 1.4, we get:

η = 1 - (1/6)^(1.4-1) = 0.51 or 51% (rounded to two decimal places)

Therefore, the correct answer is C.

In an Engine Operating in the Otto Cycle, the Final