Mass = 122kg
Length of bungee cord = 25m
Elasticity constant of cord, k = 200N/m
Friction between the fibres of the cord leads to a viscous resistance force proportional to the strain rate (proportionality constant c = 150 Ns).
Air resitance ignored

I know that before falling 25m down, I can just integrate g=9.81m/s^2 to find displacement and velocity.
The problem is with working out the equation for velocity and displacement after 25m.

If anyone can help, that would be appreciated.