Which sense is not used to tell if a machine is operating normally?

The correct answer is tasting, as this sense is not typically utilized to assess whether a machine is operating normally. When troubleshooting or monitoring machinery, technicians rely primarily on their hearing, touch, and smell.

Using hearing, individuals can detect unusual sounds such as grinding, humming, or clattering that may indicate underlying issues with machinery. Touch allows for the assessment of temperature and vibration – hot components or unusual vibrations can signal a malfunction. Smell can also play a critical role; for example, the presence of burning odors or unusual fumes can suggest overheating or mechanical failure.

Tasting is not a practical or safe method for assessing the condition of machinery, as it does not provide relevant data regarding machine performance or safety. Therefore, tasting is the sense least associated with evaluating whether a machine is functioning properly.