Bungee Jumping

When bungee jumping, hopefully there will be no impact with the ground. How can one model this situation? Here is a graph of a function f(t). A physicist has more tools to get an explicit function. For the model here is important that there is no impact. This means that the function f(t) telling how high the jumper is at time t is smooth at all time.
P.S. in a future course like math 21b, you learn how to solve this precisely and solve the differential equation f''=-10-c (a-f) + b f' where a is the height of the rope, where c depends on the rope and b is the friction. The second derivative f'' is the acceleration and -10 is the gravitational constant on earth.
Source: Golden Eye, Bond Source: Yesman