Nerida Vulchanova finished the tower for Durmstrang Institute. She magically pushed the last 117.6 N piece of marble across the roof with 43 N and it slid for 3.9 s until it flew off the roof. It lands in the last empty spot in the driveway 24 m away from the base of the tower. The marble piece will break if dropped from a height higher than 15 m, does Nerida walk away with satisfaction or wince in horror