Final answer:
The vertical axis on the m-mode display usually represents physical quantities like position in motion graphs or pressure in cardiac cycle diagrams.
Step-by-step explanation:
The vertical axis on the m-mode display represents different physical quantities depending on the context of the graph or diagram. In certain physics-related scenarios, like those involving motion graphs, the vertical axis typically represents position (in units such as meters), while the horizontal axis represents time (in units such as seconds). For example, in a graph that tracks the position over time of an object in motion, the y-axis indicates the object's displacement from a reference point. In the context of cardiac cycle illustrations used in medicine, the vertical axis might represent pressure, as shown in a graph of heart sounds over time.