General Physics Thread

I figured I'd make this thread so that we'd have somewhere to discuss events and new discoveries in the field of physics.

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I have a general physics-related question in regards to speculative fiction (specifically those featuring characters like Superman who are blatantly superhuman). Let's say you have a character like Superman or Toriko who by raw physical strength alone can amass enough kinetic energy to punch with a force greater than a hundred nuclear bombs. The question that springs eternal (at least for me) is

How do these guys go about their daily lives without destroying literally everything?

Ignoring questions like "where does all the energy come from" (a question Toriko partially answers, as does Superman) or "is one of their powers super-anchoring/super density so they don't get blown away every time they throw a punch" (I have never once seen any superhuman story address this question), how do these guys go for a walk, give a high-five or a hug, or even just open a door? If their maximum output in terms of kinetic energy is in the minimum ballpark of 500 petajoules per punch (a lowball to end all lowballs for both of these characters) versus 500 or so joules for the average human being, what happens when you apply this to other things, like sneezing, waving, yelling, or even just walking, the act of which should produce around a hundred joules per footstep?

I know I'm probably vastly oversimplifying this question by just approaching it in terms of potential energy imparted into the environment as kinetic energy, but I'd like to know. Could Superman level a city by sneezing too much? If not, how does he do it?

edited 11th Sep '14 8:50:32 AM by KSPAM

The human body has ways to control the physical force produced by its muscles. That's the reason why one can touch somebody else without always throwing them down.

I vaguely recall a rather older comic where Superman had a cold and couldn't control the power of his punches and so on.

Can't remember how it ended though.

edited 11th Sep '14 8:56:34 AM by LeGarcon

The same way humans lift things without throwing it across the room. You don't shatter a potato chip every time you pick one up.

While it can happen that someone won't know their own strength, if you live you whole life being able to fling a car across town, you'll probably have some pretty good self control.

As for superman's sneezing, I'm going with yes.

edited 11th Sep '14 8:55:36 AM by joesolo

Well, more or less what I was asking was, even if they can control their own strength, isn't there a bottom limit to how much strength is used relative to different tasks? I mean, asking a human to use 1/1000th of their full strength would be a pretty difficult demand to make of someone (at least I think). So if a human finds it difficult or impossible to limit themselves to a thousandth of their full strength, wouldn't someone with vastly superhuman strength have the same problem with disastrous effects?

If Superman can punch as hard as I stated above and a casual footstep (not a stomp or anything he would consciously put any effort towards) produces one fifth the energy of a punch in the average human, then wouldn't Superman still be dishing out Hiroshima-level damage every time he went for a stroll? Wouldn't he break his keyboard at the Daily Planet every time he gingerly tapped a key?

This is all a medical rather than physics question. I have a longer answer but it's more for the medical thread.

Required Secondary Powers. Functional super strength has to come with super-precise muscle control, which I'm fairly sure Superman has.

It's the reason He gives in the DCAU (I think) for being able to mimic voices.

Hmmm... yeah, I guess the best answer is to just chalk it up to magic, otherwise no one would be able to write superhuman characters without going into long essays about how they're totally not a danger to humanity just by existing

You could probably have a system where superheroes were ranked by how many laws of physics they could ignore if you wanted.

....I wonder if this thread will be about nothing but writers asking physics questions from their stories.

You don't need to break any law of physics to explain this. The human body does control its muscle output a) through feedback mechanisms (there are sensory nerves that measure the output) and b) through the nervous system and its structure (the "wiring" from the brain to the muscles can be rearranged and does change in response to various stimuli, especially in early childhood). So if the maximum muscle output is extremely high there'll be mechanisms that reduce how much output is generated for "simple" movements.

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