In mechanics, is shock really better expressed as jerk instead of acceleration? 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?
 A: There are definitely situations in materials science and mechanical engineering when jerk is more important than acceleration as a factor in causing damage. A term I've seen used is "load rate." This can refer to either $dF/dt$ or $da/dt$, which differ by a factor of $m$. You'll see the acronyms ALR and ILR for average and instantaneous load rate.
A steady force can't cause wave excitations, but a varying force can. For example, when you're machining something on a mill or lathe, jerk produces "chitter," which can spoil your work. Engineers designing cams work very hard to minimize the jerk of the cam follower: "Remember also that jerk translates to an impulse and excessive impact ultimately leads to scuffed and pitted cam follower." (Blair 2005)
I know of a couple of good examples involving the human body. In crewed spaceflight, astronauts are exposed during a launch not just to high accelerations but also sometimes to what's known as a "pogo," which means an oscillating acceleration in the longitudinal direction. A pogo with an amplitude as small as $0.5g$ can apparently cause extremely unpleasant sensations in the eyeballs and testicles, as well as heating of the brain and viscera (Seedhouse 2013). Heating is a phenomenon you can't get from a static force.
Another human-body example involves running injuries. Measurements using accelerometers attached to runners' feet, legs, or hips show that during a stride cycle, there are typically two different peaks, an impact peak and another "active" peak that occurs during propulsion. The impact peak has a smaller acceleration but a larger jerk, and seems to be the factor that causes injuries: "increased impact loading was associated with an elevated risk of sustaining a running injury while peak vertical force was not." (Davis 2010)
G. P. Blair, C. D. McCartan, H. Hermann, "The Right Lift",  Race Engine Technology, Vol. 3 lssue 1, August 2005
Irene Davis, quoted in http://lowerextremityreview.com/news/in-the-moment-sports-medicine/impacts-spell-injury , 2010
Erik Seedhouse, 2013, Pulling G: Human Responses to High and Low Gravity
A: Shocks by definitions are discontinuous therefore non-differentiable jumps in the relevant quantities (e.g., pressure jump across a shock mechanical shock in gas). So strictly speaking I think one cannot assign an appropriate derivative description - acceleration, a jerk, and so on. However, from a practical point of it would really depend on what quantity one might want to emphasize on, if the change in force what matters one might call it a jerk. 
A: Shock is better expressed as g (or other unit of acceleration) because f = ma. Acceleration is proportional to the mechanical force applied to the object, which in turn quantifies its internal mechanical stresses.
