What does the horizontal axis (X-axis) in a time waveform represent?

In a time waveform, the horizontal axis, or X-axis, represents time. The primary purpose of this axis is to provide a chronological framework for the data being analyzed, allowing you to observe how an object's vibration behavior changes over a specified period. By plotting time on this axis, you can see the variations in the signal's amplitude—as the signal fluctuates over time—enabling you to analyze patterns, identify anomalies, or assess the stability of a system.

As the wave progresses from left to right on the X-axis, it visually captures events in the vibration profile, showing when vibrations occur and how their characteristics evolve. This time-based perspective is crucial for understanding temporal relationships and diagnosing issues related to machine performance or condition.

The other options, such as amplitude, energy, and velocity, relate to different aspects of vibration analysis but do not accurately describe what the X-axis signifies in this context. Amplitude would typically be represented on the vertical axis, and energy and velocity are more specific parameters that do not directly correspond to the temporal dimension indicated by the horizontal axis.