i need to get rid of the x ,x is the length of the chain hanging over the edge before the chain starts to move, so when t=O x=b
this gives arccosh(1/1) = 0*sqrt[g/a]
which gives 0 = 0
which doesn't help, then i thought when i intergrated the RHS i should had a constant.
t*sqrt[g/a] +...