Superhero remedial physics

Imaginos1892 wrote:The shooter is ready and braced for the recoil (well, if he's got any sense) but the target is hit by surprise (again, if the shooter has got any sense). High power rifle bullets carry anything from 2,000 foot-pounds of energy to 12,000 (.50 BMG). That can be enough to knock you on your ass if you're not ready for it. Of course Hollywood exaggerates, but there is a nugget of truth in there somewhere.
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Firepower is not a thousand bullets that miss - it's one bullet that hits.

Ugh... Seriously...

Try playing around with this for starters:
http://www.hornady.com/ballistics-resou ... calculator

And 2000 footpounds is a medium strength cartridge, not a highpower one.

A quick and dirty example i made with the above calculator, a bullet that at V0 starts out at 800m/s and 3111 J, after just 100m the energy is down to under 2700, at 500m it´s down at just 1355 J.

And that´s just the first problem you´re facing. The fact that the impact on the shooter is HIGHER than the total bullet energy even at V0 due to incomplete energy conversion is another.

Then you have the REALLY huge problem, namely that when a bullet impacts, it does NOT transfer all the energy to the target at once.
And with a high power round, the bullet is actually quite likely to pass through a body and only impart a fraction of its total energy.

Take a look at the maths, even a 12.7x99 is still just a 40-50g bullet at a bit over 860-930m/s. Even at best that´s less than a 1400th of a persons weight.

Very simplified, even if 100% of the energy is transferred, it´s roughly equal to two people bumping into each other at walking speed.

So no, there will be no "flying backwards as if hit by a wrecking ball" antics.
And even that is with ridiculously unrealistic premises being used.




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Thucydides wrote:Mythbusters have done a lot of Hollywood myths, and the number which turn out to be real is vanishingly small. Makes you wonder where the Hollywood writers are getting their inspiration, since they don't actually see or hear of these things in the "real" world...

Rule of cool of course. Or rather, what they think is cool.



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Annachie wrote:The one that perpetually annoys me is tracing a phone call.

Yeah, totally agree.

Tenshinai wrote:
snip

So no, there will be no "flying backwards as if hit by a wrecking ball" antics.
And even that is with ridiculously unrealistic premises being used.




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Thucydides wrote:Mythbusters have done a lot of Hollywood myths, and the number which turn out to be real is vanishingly small. Makes you wonder where the Hollywood writers are getting their inspiration, since they don't actually see or hear of these things in the "real" world...

Rule of cool of course. Or rather, what they think is cool.

Actually this is one of the myths that Mythbusters took on - using a pig carcass - and totally busted it with everything up to a 50 cal MG

Tenshinai wrote:#####

Annachie wrote:The one that perpetually annoys me is tracing a phone call.

Yeah, totally agree.

If you really believe that tracing the phone call is so hard, try making a threatening phone call to the White House for some real "fun".

fallsfromtrees wrote:If you really believe that tracing the phone call is so hard, try making a threatening phone call to the White House for some real "fun".

Oh i wasn´t talking about difficulty, i was, like i expect Annachie was, talking about how it is portrayed. Which most of the time is utterly ridiculous.

And of course, if i really wanted to do an untraceable crank call, i actually know how to spoof a trace.

Actually this is one of the myths that Mythbusters took on - using a pig carcass - and totally busted it with everything up to a 50 cal MG

Yup, IIRC the 12.7 barely moved it backwards at all?

Tenshinai wrote:

fallsfromtrees wrote:Actually this is one of the myths that Mythbusters took on - using a pig carcass - and totally busted it with everything up to a 50 cal MG

Yup, IIRC the 12.7 barely moved it backwards at all?

None of them moved the pig, which was hanging as a pendulum. Adam has a tee shirt he sometimes wears "I reject your reality, and substitute my own". Seems like Hollywood's standard practice.

Although, they actually got the physics mostly correct in the new movie Interstellar - in particular the black hole physics, which is truly astonishing.

On the other side, I suspect being shot might make a person jump or flinch. Just a tiny bit.

I used to know. Well, calls that would take hours to trace anyway. But when there were still old, old electro mechanical exchanges.

Annachie wrote:On the other side, I suspect being shot might make a person jump or flinch. Just a tiny bit.

I used to know. Well, calls that would take hours to trace anyway. But when there were still old, old electro mechanical exchanges.

I talked to a vet of the Korean war a long time ago and our conversation strayed into the unrealistic portrayal of how people react when getting shot. From his experience the usual reaction was that when he shot the Chinese soldiers attacking his position they mostly just folded or stumbled before falling to the ground without a sound. At least, that was his impression of it some 45 years later.

Joat42 wrote:

Annachie wrote:
On the other side, I suspect being shot might make a person jump or flinch. Just a tiny bit.

I used to know. Well, calls that would take hours to trace anyway. But when there were still old, old electro mechanical exchanges.

I talked to a vet of the Korean war a long time ago and our conversation strayed into the unrealistic portrayal of how people react when getting shot. From his experience the usual reaction was that when he shot the Chinese soldiers attacking his position they mostly just folded or stumbled before falling to the ground without a sound. At least, that was his impression of it some 45 years later.

I have no doubt that a high calibre round can knock you on your ass. Especially if you are not expecting it, and relaxed, as opposed to braced for the shot.

I have to consider back when I was in the eleventh grade and could throw a football seventy yards flat footed. I had very few interceptions because there was just too much heat on the ball, and my accuracy was astounding.

But, I remember knocking guys down with the football caught against their shoulder pads and chest. If a football thrown from an arm can do it ...


.

I thought it interesting that Sue Richards, the Invisible Girl, couldn't make her clothes invisible as well. Which means she has to fight stark naked when invisible. No shoes while walking and running through shattered glass, hot items, etc. And no boob support either. Those things must get awfully sore flapping around during a particularly lengthy and physical battle if invisible.

And how practical is that if you need quick invisibilty. What do you do, appeal to your arch enemy to be a gentleman while you remove your knickers?

And how practical is that if you need quick invisibilty. What do you do, appeal to your arch enemy to be a gentleman while you remove your knickers?

I thought it interesting that Sue Richards, the Invisible Girl, couldn't make her clothes invisible as well. Which means she has to fight stark naked when invisible. No shoes while walking and running through shattered glass, hot items, etc. And no boob support either. Those things must get awfully sore flapping around during a particularly lengthy and physical battle if invisible.

Much worse, WINTERTIME. Anyone who tried icebathing or the like knows just how cold even a few degrees below freezing is when you have little or no clothes.
Or like, falling into snow...

But, I remember knocking guys down with the football caught against their shoulder pads and chest. If a football thrown from an arm can do it ...

An american football ball weighs almost a pound. 9 times that of a 12.7 bullet.
AND, because such a ball will not in any way pass THROUGH whoever it impacts with, it transfers all/most its kinetic energy instantly.

So, that 12.7 bullet goes maybe 300 times faster than your throw, while weighing, for simplicity´s sake, 10 times more.
Meaning that impact energy is only 30 times more for the bullet.

But the bullet does not transfer all energy instantly, nor is it likely to transfer ALL its energy(in fact, a 12.7, even hitting bone can easily loose merely 5-20% of its energy from passing through a person).

In the end, your thrown ball is actually likely to produce MORE kinetic energy transfer than the bullet.

I have no doubt that a high calibre round can knock you on your ass. Especially if you are not expecting it, and relaxed, as opposed to braced for the shot.

Uh, braced or not, will rarely have any effect at all.

Tenshinai wrote:snip

I have no doubt that a high calibre round can knock you on your ass. Especially if you are not expecting it, and relaxed, as opposed to braced for the shot.

Uh, braced or not, will rarely have any effect at all.

Mythbusters did a show on this. Hung a pig carcass on a string and shot at it with everything from a 9mm pistol to a 50 cal machine gun. Virtually no motion at all with any of them.