An 85.0-kg mountain climber plans to swing down, starting from rest, from a ledge using a light rope 6.50 m long. he holds one end of the rope, and the other end is tied higher up on a rock face. since the ledge is not very far from the rock face, the rope makes a small angle with the vertical. at the lowest point of his swing, he plans to let go and drop a short distance to the ground.