Aperson of mass m will bungee-jump from a bridge over a river where the height from the bridge to the river is h. the bungee cord has an un-stretched length of 23h and when it stretches beyond its equilibrium length it behaves as a spring with spring constant k. find an expression for the minimum spring constant k that will stop the person just before hitting the river (ignore the height of the person), in terms of m, g, and h.

22. the top of a cliff is located a distance h above the ground. at a distance h/2 there is a branch that juts out from the side of the cliff, and on this branch a bird's nest is located. two children throw stones at the nest with the same initial speed, one stone straight downward from the top of the cliff and the other stone straight upward from the ground. in the absence of air resistance, which stone hits the nest in the least amount of time?