I don't know much about physics but I know some math. So say I want to set up an experiment (hopefully easily reproducible) where I have a string (I can find out what I like about the string) tied to a spot above the ground. It is hanging straight down. Say I tie a zip lock back to it and I want to figure out what the maximum weight is that I can put into the bag without the string breaking. I guess I could repeat this experiment over and over with varying string lengths and see what the function of the weight is with respect to the weight (hopefully there's some meaningful function). However I do not have the resources currently to reproduce this experiment over and over again. Does anyone know of an equation that models what I'm trying to do? I need an approximate weight not an exact weight.