I looked around online and found that there is about 150 joules of force in a punch. And could go up to almost 1000 or so, for a strong boxer (see wikipedia link later on). That’d end up being 737 foot-pounds of force. Seems like a big but reasonable number.
I’m also a pretty big fan of manga, anime, and comics, so there are plenty of times where characters hit something. There was one thing in one particular one that annoyed me though. There was some foe trashing an area, and our protagonist for this work was not a super-powered character, nor was this something where things were super-exaggerated (comedy works usually have girls whose tiniest slap can send a man flying, those works are obvious exclusions), the protagonist was just a human who boxed or something, I forget now. But the point was, he was not superpowered, and the foe was in some ways, though I believe he didn’t have any energy fields or stuff like that which would negate projectiles.
Anyways, here’s what happened. A tank fired a round that hit the foe, but it had “no effect.” Lets just assume it was a Kinetic Energy Penetrator, which is pretty much a 5kg rod flying at 1750 m/s, the work done is quite a bit more than… oh a punch (from the link, we get an estimate here… Impacts of up to 130 joules have already been measured with hockey pucks and lacrosse balls, 450 joules in karate punches and 1028 joules in boxer Rocky Marciano’s punch), after all a 5-10kg arm flying at even record breaking speeds would still not be going nearly 2000 meters each second.
And yet, the protagonist hits the foe, which knocks him back. His human-powered punch, without any super-powered explanation, was more powerful than a tank shell, which didn’t budge the foe at all?
I’m sorry, but I like my fiction to be reasonable. Reasonable in the fiction world, not our own. If somehow they had said, our hero’s punch is inhuman, voila, case closed. Don’t even need to explain it! I’m fine without having explanations that must be believable. But in this case there was nothing to suggest our hero could hit harder than any normal human, and yet he did. They didn’t have him break through a shield or anything that made the foe immune to most weaponry, it was a simple kinetic energy case in both the response to the tank shell and the punch. That’s bad writing. At that point switch genres to comedy, where a tiny girl can hit a regular human boy with 2 million joules of energy, send him flying, and think nothing of it, and the boy just gets up and smiles, not paying any heed to the fact that he had just been smacked with enough energy to kill him a thousand times over. That doesn’t need explaining.
So, when considering force (or having your hero hit something), don’t forget about the natural laws and mechanics (especially since all of fiction is a different universe anyways, establish a few ground rules). Breaking them is fine, as long as it’s implicitly understood in some way, even if it’s a ridiculous method. However when you have an impossible juxtaposition without explanation, you’ve done wrong.