You are planning to jump off a bridge with a bungee cord tied to your ankles. The bridge deck is \(150 \mathrm{~m}\) above the water, and the cord spring constant is \(40 \mathrm{~N} / \mathrm{m}\). Because you must fall the length of the unstretched cord before it begins to stretch, you realize that the unstretched length of the bungee cord, which is adjustable, has to be adjusted based on your inertia. You enjoy thrills and want to reverse your motion just above the water surface.