🔍 Key Concepts

• Engine vibration characteristics at certain RPM ranges • Meaning of the word critical in engineering/machinery contexts • Difference between operational limits and design maximum capability

💭 Think About

• Which term is commonly used for an RPM range that the manufacturer warns you to avoid or pass through quickly because of harmful vibration? • Think about which option describes a danger point for machinery rather than just a high or designed speed. • Which choice sounds like a specific, identified range on a tachometer that may be marked with a red or shaded band?

✅ Before You Answer

• Identify which term is associated with avoid operating continuously due to vibration or stress. • Separate the idea of maximum possible speed from unsafe resonance speed. • Consider standard engineering language: which term is most often linked to resonance and excessive vibration?