Piston displacement specifically refers to which of the following?

Piston displacement specifically refers to the space in the cylinder that is swept or passed through by the piston as it moves from the top of its stroke to the bottom. This measurement is crucial as it determines the volume of the cylinder that is utilized for the combustion process in an engine.

Understanding piston displacement helps in calculating the engine's overall capacity, efficiency, and performance. The larger the piston displacement, the more air-fuel mixture can be drawn into the cylinder, which generally leads to more power being generated. This concept is foundational in engine design and mechanics.

The other options—weight of the piston, volume of air in the cylinder, and length of the piston stroke—do not accurately capture the definition of piston displacement as they refer to different characteristics of the engine components or the combustion cycle.