Riddle: Dynamite is a tool that can be used to cut down trees. To cut a tree 18 inches in diameter requires five sticks of dynamite: one on the north, south, east and west sides of the tree, and the fifth stick on the side to which the tree should fall. During construction of a dam, a tree 18 inches in diameter was completely covered by water. Since the treetop was fouling the boat's propellers, it had to be cut down. A diver went down and put a stick of dynamite on the four sides of the tree. Since the current is flowing south at 2 knots per hour, on which side of the tree would you instruct the diver to put the fifth stick of dynamite if you wanted the tree to fall north?
Answer: It doesn't matter where the fifth stick is placed, since the tree won't fall in any direction. Being wood, it will float and rise to the surface.