Sophia is mountain climbing when she unfortunately slips and falls off a ledge. She is secured with a 20-m-long dynamic climbing rope that only begins to stretch after she has fallen 20.0 m below the ledge. Sophia’s mass is 60.0 kg, and the rope obeys Hooke's law, $F = -kx$, with k = 70.0 N/m. Ignoring air resistance and the mass of the rope, estimate the distance d below the ledge that Sophia’s harness will be when she is momentarily motionless. Assume Sophia can be treated as a point mass.