Solution: The mixing mass of gasoline and air in the cylinder in a working cycle: m mixing =ρV= 1.35kg/m? × 1.8× 10^-3m？ =2.43× 10^-3kg

Gasoline quality: m =115× m mixture =115× 2.43×10-3 kg.

Total mass of gasoline burned in 2600 working cycles within 1min: mtotal = 2600 m = 2600×115× 2.43×10-3 kg = 0.4212 kg.

Heat released by gasoline combustion: q = MQ = 0.4212kg× 4.6x107j/kg =1.94x107j.

Work done by automobile engine: w = pt = 75×103w× 60s = 0.45×107j.

Automobile engine efficiency: η = w/q = 0.45×107j/10.94×107j = 23.2%.

A: Omit.

You got it?