Question

Technician A says that horsepower equals the ability to perfoem work at a rate of 33,000 foot-pounds per minute. Technician B says that in many vehicles, as little as 15% of the potential energy in the fuel is delivered to the drive wheela. Who is right? Explain.

Answer 1

Answer:

  Both are

Explanation:

The definition of a horsepower is 33,000 ft·lb/min, so Technician A is definitely right.

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In many vehicles the thermal efficiency of their gasoline engine is no higher than 20%, so it is likely that Technician B is also correct. Efficiency is lower at idle and when the engine is not called upon to do much work.

(Diesel engines may have a thermal efficiency approaching 40%. Toyota has developed technology that may give some of their gasoline engines a thermal efficiency of up to 38%. These are not technologies that are applied in most vehicles.)