Last weekend, I had a situation come up while running my Karma game for some friends. They came to a locked wooden door, and nobody had any lockpicking ability or keys. Since it was a simple wooden door, they said they would just break it down. As this was not meant to be an overly complicated part of the session, I made it a simple athletics check based on strength instead of endurance. I set the difficulty low (12), because, again, it was not meant to be a big deal. But as is generally the case with such things, it soon turned into a comedy of errors. The character that actually had ranks in Athletics botched the roll and broke his foot for his troubles. Another character attempted the check untrained, and while he didn't botch only managed to put a crack in the door. Then the third character says "wait a minute. I don't have athletics, but I have a specialty in Karate. You mean I can't use THAT to kick in a wooden door?"
So this whole thing got me thinking about breaking stuff, and what is actually involved. Most game systems relegate this to strength. But that doesn't really seem right. So I went looking for information on how to calculate the break point of materials and came across all of these complex physics equations and...frankly...I am not going to expect gamers to perform physics equations to break down a door. I need to come up with something simple and clean.
But to do THAT, I need someone to help me with some general information. I'm trying to get a general idea of the yield and breaking points of various materials, measured in psi. I found a few charts that measured this is MPa, but then that needs to be converted in such a way as a normal person can understand it.
So are there any science geeks interested in helping me out with this quandry?
recommend this
email
print
link to this page
Comments: 8
Most of the stuff I've found on the internet has been of the "well, it depends" variety. I realize that different types of annealed glass have different break points. I know different grades of steel have diffrent yield points. What I'm interested in are very bare-bones averages that I can then use to come up with an easy means of translating to a game table.
That is pretty much the direction I was going with it. But before I can boil it down to how to calculate the check, I need to figure out what the yield and break points are for things like wood, stone, glass, steel, etc. Once I have an average, I can determine how to work that into the game mechanics to come up with a realistic but easy method.
No, I realize all that. I know there are equations to calculate specific things. What I need is a bare bones average. i.e. wood yield strength is X and break strength is Y. I KNOW there will be variables depending on different woods. But players aren't going to know if a door is maple or oak or pine, for example. I'm trying to get general averages.
Just type in Pascal and pressure into wikipedia and it will give you a conversion table for many other common units of pressure.
Divide MPa by .0068947 to get approximate psi.
I have no idea what your game is about. But I think that smartly placed pressure in the right place would be the key. I would guess this to be related to intelligence, athleticism, and body mass.
Pressure = Force/Area
Force = mass x acceleration
So have a large mass decelerate from a high velocity to a low velocity over a short period of time (impact) and be focused over a small area.
Ever see those glass breaking hammers for getting out of a car? Just a little pinpoint with a heavy weight behind it.
I would generally say that any one or two healthy grown adults can crash a standard door. Of course they may break a foot or a shoulder in the process ... oh well ...
All of this aside ... never forget the first principals of being a gamemaster:
Don't let the details get in the way of a good game.
Maintain control ... you use the dice, they don't use you.
When in doubt, roll some dice and consult a notebook to give yourself time to think.
Sounds like you have a good game going.