# How to relate Grms with everyday experience

1. Nov 23, 2014

### likephysics

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?

2. Nov 23, 2014

### SteamKing

Staff Emeritus
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.

http://en.wikipedia.org/wiki/G-force

3. Nov 24, 2014

### likephysics

I understand 25G itself if very high.
Can I make the same statement when the magnitude is 25Grms?

4. Nov 24, 2014

### SteamKing

Staff Emeritus
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.