A 75kg person jumps off a tower with a bungee cord tied around their leg. The cord obeys Hooke's Law and has a cord constant value of k=50 Nts/m. After falling a distance of 15m, the cord begins to stretch. Neglecting air resistance and the mass of the cord,
a) calculate how far below the tower the person falls when coming to a complete stop;
calculate the maximum acceleration felt by the person.

We are having trouble since there are two unknowns, how much the cord stretches, and the total distance the person fell.