Vibrations — definition of frequency Does “frequency of vibrations” mean the number of cycles per second (measured in hertz, Hz)?
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AYes
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BNo
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COnly for sound waves
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DOnly for electrical signals
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EDepends on amplitude
Answer
Correct Answer: Yes
Explanation
Introduction / Context:In vibration analysis, frequency quantifies how often a periodic motion repeats. Whether analyzing machine imbalance, structural resonance, or signal processing, the definition is consistent across domains.
Given Data / Assumptions:
- Periodic motion with a well-defined cycle.
- SI units are used: 1 hertz (Hz) = 1 cycle per second.
- Amplitude or damping does not redefine frequency.
Concept / Approach:Frequency f is the reciprocal of the period T: f = 1 / T. It counts complete cycles per unit time and is independent of amplitude. In angular terms, ω = 2π f (rad/s). This definition applies to mechanical vibrations, acoustics, and electrical waveforms alike.
Step-by-Step Solution:
Identify the repeating pattern (one full cycle).Measure the time for one cycle → T seconds.Compute frequency: f = 1 / T cycles per second = Hz.Verification / Alternative check:For a rotating shaft at 1200 rpm: f = 1200 / 60 = 20 Hz. The same calculation is used for sound waves and electrical signals, confirming universality of the definition.
Why Other Options Are Wrong:
- No / only for sound/electrical: Restricting to specific domains is incorrect; the definition is universal.
- Depends on amplitude: Frequency is independent of amplitude; changing amplitude does not change cycles per second.
Common Pitfalls:Confusing angular frequency ω (rad/s) with f (Hz). They are related by ω = 2π f but are not the same unit.
Final Answer:Yes