Physics of Shaolin Soccer
So my friend showed me this video ( http://www.youtube.com/watch?v=uV-dqhGd-YQ ) and at around 2:19, one player kicks the ball incredibly fast into the chest of an opposing player and the momentum of the ball pushes the player into the goal. So I wanted to figure out just how fast the player had to kick the ball to get both the ball and the opposing player to fly into the goal.
Seeing as how the man who got the ball kicked into his chest was a rather large fellow, I assumed his weight to be 100 kg. I found that the mass of a FIFA recognized level 5 ball is 0.450 kg. I also assumed that the chubby man was standing at the edge of the penalty box (16.5 m from the goal) and when hit by the ball, he and the ball both took 2 seconds (as recorded by the timeing in the video) to get into the goal.
Thus, we have the following:
Mass of man: 100 kg
Mass of ball: 0.450 kg
Distance and time for ball and man travel into the goal: 16.5 m in 2 seconds
-therefore, velocity of man and ball is 8.25 m/s
Initial velocity of man: 0 m/s
Using the conservation of momentum formula for an inelastic collision (because once the ball hits the man, the ball and man move together):
Initial momentum = Final momentum
m(ball)v(ball) + m(man)v(man) = [m(ball) + m(man)]v(ball + man)
(0.450 kg)(V) + (100 kg)(0 m/s) = [0.450 kg + 100 kg] (8.25 m/s)
V is of the kicked ball is roughly 1,841 m/s or 4119 mph
The fastest kick ever recorded in game was 114 mph (50.96 m/s) by David Hirst.
Gotta give it up to Shaolin Soccer!