You and your team are tasked with evaluating the parameters of a high-performance engine. The engine compresses the fuel-air mixture in the cylinder to make it ignite rather than igniting it with a spark plug (this is how diesel engines operate). You are given the compression ratio for the cylinders in the engine, which is the ratio of the initial volume of the cylinder (before the piston compresses the gas) to the final volume of the cylinder (after the gas is compressed): V_i:V_f. Assume that the fuel-gas mixture enters the cylinder at a temperature of 22.0 °C, and that the gas behaves like an ideal gas with γ = 7/5.

(a) If the compression ratio is 15.4:1, what is the final temperature of the gas if the compression is adiabatic?

(b) With everything else the same as in (a), what is the final temperature of the gas if the compression ratio is increased to 17.0:1?

(c) Everything else being the same, for which compression ratio do you think the engine runs more efficiently? Give a qualitative argument for your answer.