How to relate Grms with everyday experience

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Discussion Overview

The discussion revolves around understanding and relating the concept of Grms (root mean square acceleration) to everyday experiences, particularly in the context of high accelerations such as 25Grms. Participants explore comparisons to familiar situations like airplane takeoffs and earthquakes.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant seeks to relate 25Grms to common experiences, questioning if it is comparable to vibrations during a plane takeoff or a magnitude 4 earthquake.
  • Another participant asserts that 25Grms is significantly worse than both scenarios, likening it to a severe impact, such as crashing into a wall, which could lead to serious injury or death.
  • A participant acknowledges the high nature of 25G but questions if the same applies when discussing 25Grms specifically.
  • Another participant explains that the RMS value is used to estimate an average of varying quantities and notes that the peak G value for sinusoidal variation would be higher than the Grms value, emphasizing that 25G is high regardless of the context.

Areas of Agreement / Disagreement

Participants generally agree that 25Grms represents a high level of acceleration, but there is some uncertainty regarding the implications of RMS versus peak values and how they relate to everyday experiences.

Contextual Notes

The discussion includes varying interpretations of Grms and its implications, as well as the potential for misunderstanding the significance of RMS values in practical scenarios.

likephysics
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I need to something to relate the vibrations (Grms) to everyday life. How can I explain how much 25Grms is.
Is it similar to vibrations you experience during a take off or is it similar to vibrations you feel during a Mag 4 Earth quake?
 
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likephysics said:
I need to something to relate the vibrations (Grms) to everyday life. How can I explain how much 25Grms is.
Is it similar to vibrations you experience during a take off or is it similar to vibrations you feel during a Mag 4 Earth quake?

No, 25g is much worse than either of those. It's like riding in a car and slamming into a wall. Serious injury or death can result from exposure to such high accelerations.

There's a table of g-forces in this article:

http://en.wikipedia.org/wiki/G-force
 
I understand 25G itself if very high.
Can I make the same statement when the magnitude is 25Grms?
 
likephysics said:
I understand 25G itself if very high.
Can I make the same statement when the magnitude is 25Grms?

The RMS value of a varying quantity is used to estimate the 'average' of that quantity, especially if the magnitude varies between positive and negative values, where a simple arithmetic mean would give misleading or useless information.

For example, the arithmetic mean of a quantity which varies sinusoidally would be zero.

http://en.wikipedia.org/wiki/Root_mean_square

The value of 25Grms, as an RMS value also implies that the peak G value is even higher: Gpeak = SQRT(2)*Grms for sinusoidal variation.

25G is high, regardless of whether it is RMS, peak, or just plain average. You don't often encounter such accelerations in daily activity, or, you don't live to talk about them, that is.
 

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