In a movie, the hero jumps straight down from a bridge?

in a movie, the hero jumps straight down from a bridge onto a small boat that continues to move with with no change in velocity. what physics is being violated here?

 

Answer

1: If the hero looks down and sees the boat below him, then jumps, the boat won't be there any more by the time he gets to water level. The boat keeps moving forward, so he will miss it and hit the water instead. In order to hit the boat, he would actually have to jump BEFORE the boat gets to the bridge and time it just right. #2: If he should happen to drop into the boat, his extra mass is added to the mass of the boat. Since momentum is always conserved, the boat should slow down because of the extra mass. (p=mv), rather than continuing to move with no change in velocity. #3: This one depends on how high the bridge is. But if the bridge is really high, and he managed to hit the boat, then the hero would hit the boat with so much force that he would probably break his legs when he hit the deck (or simply break through the deck if its a small boat). Not a good situation for a movie hero who has bad guys chasing him.