You are on the top of a 200m cliff. You have a 150m long rope and a knife. You can only tie your rope where you stand, or 100m below on a tree. Can you reach the bottom of the cliff alive, and how?
Any Free fall is considered deadly.
trick is a loop
Suppose the cliff is point C and the tree is T and the midpoint is point M.
Cut (1st and last cut) 100M of rope and put into pocket. Tie the other 50M at C then descend to M. Convert the end of this rope into a loop at the point M. Lubricate the loop then pass the 100M rope through, to make a 50+50 double rope. Descend to T then retrieve the entire 100M.