Some expensive electronics or mechanical devices are designed to be shock-resistant. However, the manufacturers often market the level of shock-resistance in units of g-force (I know g-force is really a measure of acceleration). I'm not really convinced that that's the proper unit.
In fact, the Wikipedia article for mechanical shock describes shock as a sudden acceleration or deceleration. Here, the term "sudden" seems to imply that the acceleration or deceleration is not constant during a shock, which would mean that there should be a jerk component to the equation that describes the movement or position of the object as a function of time.
So here are my three related questions:
- Is shock better expressed as g-force per second? If not, why (i.e. why is g-force a better unit)?
- When you bang a smaller object that is reasonably rigid (e.g. a wristwatch with stainless steel case and bracelet) against another object that is reasonably massive, immovable, and rigid (e.g. a brick wall), how does the plot of position as a function of time actually look like, supposing we can record time and distances with extreme precision?
- Do common mechanical devices suffer mostly from high acceleration or from high jerk?
Update The ISO 1413 shock resistance standard seems to give some clues. The testing procedure consists of letting a 3 kg hard plastic hammer traveling at 4.43 m/s hit a watch. Which suggests that we really care about the instantaneous transfer of energy or of momentum. But how fast does the transfer happen? Is it in the millisecond or nanosecond granularity?