Final answer:
In theory, an engine with no frictional losses would have an efficiency of 100%, but this is not attainable in the real world due to other types of inefficiencies, even for a Carnot engine.
Step-by-step explanation:
Engine Efficiency without Frictional Losses
If an engine were constructed in such a way that there would be no losses due to friction, it would theoretically have an efficiency of 100%. The efficiency of an engine is defined as the ratio of the work output to the heat input, expressed as a percentage. In a frictionless scenario, there would be no energy wasted as heat due to friction, allowing all of the input heat energy to be converted into work.
Engine efficiency is typically less than 100% in real-world scenarios because there are always some energy losses, usually as heat due to friction between moving parts and other processes such as air resistance. However, with the hypothetical assumption of no frictional losses, the engine would not lose any energy in these ways, leading to a maximum possible efficiency. This is only possible in theory as all real engines experience some form of loss.
Moreover, this question may hint at the concept of a Carnot engine, which is a theoretical model of a heat engine with maximum possible efficiency that operates between two heat reservoirs. However, even a Carnot engine cannot achieve 100% efficiency unless the temperature of the cold reservoir is absolute zero, which is not physically attainable.