I'd like to build a simple desk; just a single plank of wood (or a few side-by-side) with solid supports on each end of the desk. What I'm trying to figure out is how thick a plank I want to use for the surface. Ideally, the desk will be able to support my weight (since sometimes I stand on my desk to change lights, etc), plus the weight of my computer stuff, plus some amount of safety margin.
So, supposing I have a desk surface that's eight feet wide, what equation do I need to use to figure out how thick it needs to be to support, e.g., 300lbs, placed in the middle? What properties of the wood type that I'm using do I need to determine? Is this an issue of tensile strength, or something entirely different?
This is obviously more a structural engineering problem than a physics one, but I didn't see a structuralengineering.stackexchange.com. Sorry if I posted to the wrong place.