Guys, this is because gravity is not a constant, it's an acceleration. Falling objects increase velocity by 32.2 ft/s or 22 mph every second. Ignoring wind resistance an object starting from rest (0 ft/s) will reach 32.2 ft/s after one second, 64.4 ft/s after two seconds, and so on. Thus the arrow will drop faster at the end and you'll see an arc like you did (the arc is because of the increasing rate of vertical drop). Also the arrow slows down and thus will travel in more of an arc than if it didn't.