So there is a big building with lots of floors in a heavily populated city (new york or something, idk). And this building has a rooftop you can walk onto (like it has stairs leading to the rooftop). So lets say there is a guy lying on the rooftop (thanks for those who answered that question) and another guy is standing next to him. They are both on the edge of the rooftop (thanks to Rudd for answering that question). Now the guy who is standing (joe) picks up the guy who is lying down (bob) and throws bob off the rooftop. So how long would it take Bob to hit the ground? Obviously there is no way to be exact, just give a good estimate. Let's assume the building is like 15 stories high or something. NOTE: building in picture is not to scale