Final answer:
The question involves the start-up procedure of a jet engine and relates to the principles of mechanical and aeronautical engineering, with specific mention of engine efficiency, operations, and procedures as well as the thermodynamics of engines, including diesel and turbine engines.
Step-by-step explanation:
The question pertains to the proper procedure for starting a jet engine, specifically regarding at what percentage of N2 (the rotational speed of the high-pressure compressor) the thrust levers should be moved to IDLE. This falls under the subject of aeronautical engineering, and more generally, mechanical engineering, as it involves the understanding of jet engine operations and procedures.
The functioning of a diesel engine is described in the context of an ideal diesel cycle. Combustion in such engines occurs when air is adiabatically compressed to a high temperature, eliminating the need for a spark plug. This principle is similar to that applied in jet engines, where air compression plays a critical role in the combustion process.
Moreover, a grasp of thermodynamics is necessary to understand engine efficiency, as exemplified in the equation W= Qh - Qc. A 100% efficiency, which is hypothetical, would imply that Qc is zero, indicating all heat input Qh is converted to work W. Real-world engines have efficiencies far lower than 100% due to various losses and real-world constraints.
The efficiency of automobile engines and their maximum climbable grade are also topics that would be covered in a mechanical engineering course. The question about maximum grade relates to the power output of the engine and additional factors such as frictional forces.