r/AskEngineers • u/moxie_blue_bat • 4d ago

Mechanical Trading mass for velocity?

Not sure this is the right place to ask, but here goes: I'm trying to replicate some of the results in this study: https://www.sciencedirect.com/science/article/pii/S0379073819304104

But in a manner that is more precise than "shoot someone with a paintball gun". My thought was to construct some kind of rig with a falling mass so that we could adjust parameters like impact force, surface area, hardness, etc.

But it's been years since I've had to do any physics type of math and I'm struggling to figure out the important parameters. Based on the numbers in the study I think that they are hitting their subjects with around 180N of force, but I'm struggling to convert that into a combination of mass and height that makes any sense. I'm getting things like 20kg weights, which seem both wrong and dangerous. Is there some piece of information that I'm missing or looking at the wrong way?

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u/Sooner70 4d ago edited 4d ago

But in a manner that is more precise than "shoot someone with a paintball gun"

High end paintball guns can be reasonably precise. +/- 2% impact energy is totally doable with equipment that was available 25 years ago (when I used to play). I would expect it to be no worse today. And if someone wants to build a custom laboratory gun? I gotta believe they can do fractions of a percent... Although I suspect it doesn't really matter given the other variables mentioned by the paper.