A uniform chain of total length 8 metres, settle 1 metre above the ledge and 2 metres hang on the other side. If x represents the length. The motion of the chain is

where v is velocity and g is a gravitational constant

show that by making the substitution we obtain

now do i have to integrate this in order to subsitute?

any help on this would be appreciated as i have no idea where to start cheers people!.