Tarzan swings on a vine from a cliff to rescue Jane, who is standing on the ground surrounded by snakes. His plan is to push off the cliff, grab Jane at the lowest point of his swing, and carry them both to the safety of a nearby tree . Tarzan's mass is 79.1 kg, Jane's mass is 42.5 kg, the height of the lowest limb of the target tree is 11.9 m, and Tarzan is initially standing on a cliff of height 21.7 m. The length of the vine is 33.1 m. With what speed should Tarzan push off the cliff if he and Jane are to make it to the tree limb successfully?