(This is not a homework question!) An experimental set up shows 2 rigidly placed stands, with pieces of metal links joining with each other forming a chain. The chain is hung from the top point to point of the stand. If we were to plot a graph, with $d$ being the dependent variable and the number of links we put into the chain to make the overall length of the chain longer, ie the length of the chain is considered the independent variable. We get a graph:
From here we see, we get a non-linear increasing trend line. What would be the physical reasoning for such non-linear trend.
Attempt to answer: With the increase of links to the chain, ie by increasing the length of the chain, the links at some point stack on top of each other, which may lead to increase of mass therefore more gravitational pull, therefore leading to equal increments in giving rise to unequal increments in d.