During my relatively short life I have fallen many many times , several come to mind as to be the most notable and all of which are due to gravity. One of these is when me and my friends were riding our bikes and their was a ledge separated from another with about an eight foot drop. I assumed that I could travel fast enough to cross the gap. keep in mind this was two years before I leaned about trajectory so a peddle and peddle and go straight off and immediately started to travel downward. I broke the bike and was walking with a limp a for about a week. Trajectory and gravity meant that my path starts to move downward immediately and I was never going to make it. I also wiped out quite spectacularly once on a boogey board.