A 55.0 kg girl is roping through the top of a tiny tree. She quickly swings down from her 12.0 m high perch and grabs a 21.0 kg dog as she swings. They barely swing back up to a tree limb. How high is this tree limb?

1 answer

you know the initialPE, and the final PE is not known

intial=final
55*g*12=(55+21)g*h
solve for h.