For every sport there is something that changes momentum. For example in basketball if someone absolutely posterizes a player from the opposing team it will get the whole team fired up and playing hard. Gymnasts slamming people? Are you talking about wrestling or MMA?

A penny though often abandoned or given away is more than one may think. Lots of people can save pennies and it can add up same as any other form of currency. This also allows people to create perfect change. For many things, you’d have to change if you did away with the penny such as a different sales tax.

The need for fighting in proffessional hockey is a big thing. The act of a fight or big hit does more for momentum than one may think. The fight will also gain the player who was in the fight more respect for standing up for his team and trying to regain momentum for his team. Fights also bring more fans to the game. Many fans would like to see a higher level of physicality versus virtually none at all which is cool to watch, but not like a game with lots of physicality.