A girl climbs up a tree with a 2 kg rock. When she is 30 m above the ground, she drops the rock from rest. Using coordinates where y = 0 at the point where the rock is let go from (not at the ground!), answer the following questions (give all answers in S.I. units) A. What is the gravitational potential energy of the rock right before it is dropped? Selected Answer: [None Given] Question 20 B. What is the gravitational potential energy of the rock right before it strikes the ground? Selected Answer: 588