Bradley Cooper could take down Vince Vaughn?

In football or life in general, it's not really size that matters. For one, Vaughn is not expecting to get hit since it's touch football and for two football has a "rule" of "lower man wins", meaning whoever gets the lowest wins the fight, however strength plays into that a good deal, but if you're hit and don't know it's coming it doesn't matter much how much bigger or stronger you are.

aqib4,

Watch football sometime and take note of how FORCE = MASS x ACCELERATION.

Have you ever heard of a corner blitz? It's where generally one of the smaller players on the field tries to tackle the quarterback (in the NFL, quarterbacks are usually quite large).

If a smaller plays accelerates rapidly and intends to hit an immobile or slow moving player, the results can often be devastating for the immobile/slow-moving player who is receiving the hit. It's just physics.