Reel Physics: Demolition Man - Bashing Brittle Bars

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Demolition Man - Bashing Brittle Bars

Watch as Colby and Jason debate Sylvester Stallone's bar breaking ability.

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Hey Everyone!
It's time to head back to the days when Wesley Snipes was an A-List movie star.
This week is Demolition Man where the 90s special effects were absolutely awe-inspiring.

As always, thanks for watching. Please submit your suggestions for future episodes here or in the forums. You can also email us at reelphysics@escapistmag.com.

Anyone up for Taco Bell?

Jason Dean
REEL PHYSICS

Sly-as-Willy-Wonka absolutely cracked me up for some reason.

Trying to watch the HTML5 version. It stops playing close to the 3 minute mark. Downloaded a copy and every video player I can find crashes around there. Just so you know. (This is on Ubuntu Linux, FYI, tested with VLC and Totem Player.)

Nice two-fer on the cheeseball action movies today. Man I loved these films.

Speaking of Ahnold, why not explore the possibility of him double wielding a rail gun without injury, or for that matter anyone firing even a single one and surviving the recoil

As usual top notch work
like the video, and agree with the frozen bars
( actually i thought they'd be even weaker than that )
however..

it takes the assuming of impossible things for this to be true, so i still give the premise
of the scene a fail

with the scene relying on magic for all intents and purposes as physics just wont allow for such
a tiny object to absorb all that energy because that's just not how heat works.

even assuming it's a Bose-Einstein condensate that doesn't give it the ability to absorb
such extreme amounts of energy, considering the superconductivity of such a gas/fluid/thing.
i imagine it would simply vaporize as it splashes against the floor and boil away leaving behind
water vapor condensation because to get anything near absolute zero it has to be submerged in,
or cooled by another object the air and other objects in the room would insulate the actors
( and metal bars ) perfectly well

it could be tested by dropping a cube of gas on the ground,( isn't that an odd sentence )
but absolute zero is a task beyond us mere mortals
i don't keep a laser cooling rig in the basement!

interesting thought!
even if it absorbed all the thermal energy in the room, it would expand to an extreme size,
i don't know the math but i'm guessing it would make it uncomfortable or impossible to breathe
comments?

to the demolition man i say,

have an ice day, ( in hospital ).

Yay, a great goldey oldey!!!!
And wow, it is possible.

Always wondered how supercooled steel bars would react to that.
Of course such a cooling blue drop thing is impossible, but here's another question:
Would Stalone not get terrible burns on his arms from the supercool steel he's touching?

I think he would stick to them, and then his skin (and probably some subcutaneous fat/muscle tissue as well) would rip off as he kept going.

I have to admit I don't actually understand this. So a person at above average speed(or maybe even average running speed since the force is way over what's needed) can run into steel bars and break through?

Kenjitsuka:
I think he would stick to them, and then his skin (and probably some subcutaneous fat/muscle tissue as well) would rip off as he kept going.

depends on the temperatures involved, at super low temperatures you'd vaporize tiny amounts of liquid/solid gas that are stuck to the object and it would create a tiny barrier between you and the object, your hand is so hot it's is like touching a soldering iron on an ice cube in this situation.

it's called the 'Leidenfrost Effect'

this is also the reason the bars, and actors are quite safe from a flash freeze in the first place
there's a nice video here: http://www.youtube.com/watch?v=gjsMV1MglA4

anian:
I have to admit I don't actually understand this. So a person at above average speed(or maybe even average running speed since the force is way over what's needed) can run into steel bars and break through?

Only when the bars have been subjected to extremelt low temperatures. Frozen things break very easily.

The Lugz:

Kenjitsuka:
I think he would stick to them, and then his skin (and probably some subcutaneous fat/muscle tissue as well) would rip off as he kept going.

depends on the temperatures involved, at super low temperatures you'd vaporize tiny amounts of liquid/solid gas that are stuck to the object and it would create a tiny barrier between you and the object, your hand is so hot it's is like touching a soldering iron on an ice cube in this situation.

it's called the 'Leidenfrost Effect'

this is also the reason the bars, and actors are quite safe from a flash freeze in the first place
there's a nice video here: http://www.youtube.com/watch?v=gjsMV1MglA4

Is that effect the one that allows you to gargle liquid nitrogen? (but not swallow it)

Interesting, so for a follow-up question: how fast can a person accelerate on ice?

EDIT: whoops, got tabs mixed up.

Although... If you're looking for suggestions, how about analyzing the first time Agent J uses the Noisy Cricket during that chase scene in MIB?

kailus13:

The Lugz:

it's called the 'Leidenfrost Effect'

this is also the reason the bars, and actors are quite safe from a flash freeze in the first place
there's a nice video here: http://www.youtube.com/watch?v=gjsMV1MglA4

Is that effect the one that allows you to gargle liquid nitrogen? (but not swallow it)

Protip, NEVER gargle encapsulate or contain any super hot or cold substance, give it a way to escape!
if you equalize the temperatures enough you'll flash-freeze, it's extremely dangerous.

that said yes, that's the effect i'm talking about, you are so hot, compared to the object
it simply sublimes into a gas and creates a bubble under itself that creates an excellent thermal
barrier, i did include a youtube clip with my original post it's very informative

the host is a well known science buff, so it's well presented.

Ok you lost me with all the math. Did we just conclude that this was plausible?

canadamus_prime:
Ok you lost me with all the math. Did we just conclude that this was plausible?

Pretty much, if the steel bars are cooled to near absolute zero temperature. In fact, he can pretty much pulverize those bars when running at top speed.

Why the hell do they keep showing the column buckling diagrams (Pole with load on top)?
The beams obviously aren't buckling (and they aren't using those equations).

Also, on another note, the welds on bars are already significantly weaker than the bars themselves, and already have brittle properties, freezing them would no doubt make them even easier to snap out.

Burn, imperial system!

Also, I actually giggled a bit at the Fsly and asly.

Keep the show going strong, excellent content.

I'm always amazed by the episodes of this show that actually prove to be plausible

Demolition Man is such a great movie how could anyone have ever even doubted its scientific accuracy?

Wow, this episode was brilliant, by far my favourite yet. I laughed out loud at "What seems to be your boggle", I really need to watch Demolition Man again now and all the references were really funny.

Ugh, and now I need to watch The Running Man again too!

Kenjitsuka:
Yay, a great goldey oldey!!!!
Would Stalone not get terrible burns on his arms from the supercool steel he's touching?

I think he would stick to them, and then his skin (and probably some subcutaneous fat/muscle tissue as well) would rip off as he kept going.

In the movie they don't stick, meaning he probably wouldn't get any burns from the cold. As to would they stick, that depends how wet his skin is. Dry skin won't stick to a frozen pole, but wet skin will. So the question is what is happening to his sweat from all that fighting? is the room cold enough that he is not sweating?

pretzil:
Why the hell do they keep showing the column buckling diagrams (Pole with load on top)?
The beams obviously aren't buckling (and they aren't using those equations).

Also, on another note, the welds on bars are already significantly weaker than the bars themselves, and already have brittle properties, freezing them would no doubt make them even easier to snap out.

1) Is that what they are showing? one diagram had the pole free at one end, so I imagine they are the correct formulae for the purpose. Now the video of the pole being pulled apart by a machine was incorrect for purpose.

2) I don't see that there were welds, solid bars from floor to ceiling and embedded in concrete. That said, you made me think something else that makes this more plausible - that electric raygun probably did a number on the bars too. Anecdotal, but enough to make me wonder, my uncle put a shovel through a high voltage line and the shovel basically disintegrated under the current. Luckily, dry wooden handle so I still have an uncle. So it seems that electricity has a bad effect on the strength of metals too, perhaps it ruins the tempering.

Phishfood:

pretzil:
Why the hell do they keep showing the column buckling diagrams (Pole with load on top)?
The beams obviously aren't buckling (and they aren't using those equations).

1) Is that what they are showing? one diagram had the pole free at one end, so I imagine they are the correct formulae for the purpose. Now the video of the pole being pulled apart by a machine was incorrect for purpose.

The pictures show a load applied at the tip, but acting in axial compression, the 4 pictures: 'Pinned-Pinned','Free-Fixed', 'Fixed-Fixed' and 'Pinned-Fixed' are only applicable for buckling problems as they allow you to determine the equivalent length of a collumn. Google 'Euler Buckling' and you will see those pictures everywhere, Google 'Cantilever Beam' if you want to see the pictures they should have used

Phishfood:

2) I don't see that there were welds, solid bars from floor to ceiling and embedded in concrete.

Simply look at the pictures shown in the video and you can see that the bars are not full roof length, they have flat strips running horizontally every foot or so, unless they are just sitting there (which in the stunt they are...) they would have to be welded in place.

pretzil:

Also, on another note, the welds on bars are already significantly weaker than the bars themselves, and already have brittle properties, freezing them would no doubt make them even easier to snap out.

Glad I'm not the only one to notice this.

And the film actually bares this out as the bars do not deform themselves but clearly break at the welds on the cross beam, as you can see in the footage.

Sorry, guys, right conclusion, wrong reasoning.

Okay guys now do a scene from fortress.

The Lugz:

Kenjitsuka:
I think he would stick to them, and then his skin (and probably some subcutaneous fat/muscle tissue as well) would rip off as he kept going.

depends on the temperatures involved, at super low temperatures you'd vaporize tiny amounts of liquid/solid gas that are stuck to the object and it would create a tiny barrier between you and the object, your hand is so hot it's is like touching a soldering iron on an ice cube in this situation.

it's called the 'Leidenfrost Effect'

this is also the reason the bars, and actors are quite safe from a flash freeze in the first place
there's a nice video here: http://www.youtube.com/watch?v=gjsMV1MglA4

Thanks for the video link and explanation! :D

There's something else to consider. This was rapid cooling, not just a steady cooling process like the numbers seen use.

The rapid nature of the process may change the structure and hardness of the steel to a significant degree IF it is high carbon (not mild, mild has around .3-.6% carbon) steel. For example, I worked as a professional blacksmith to get through college. I made blades all day every day that I wasn't in school. Sometimes I would volunteer at the local children's history museums and the kids' favorite lesson was the difference between hardness and strength.

I would heat the end of a bar of high-carbon steel (52/100 is what I had in stock) to an orange glow and then plunge it into the slack tub (water). The process of rapid cooling caused the metal's hardness to increase significantly and then I would shatter the high-carbon steel at room temperature with a hammer and anvil. It was not hard to do.

Now, that being said, I have never had access to magic liquid nitrogen that would transform room-temperature steel instantly into absolute 0. So I do not know if that would create the same kind of impact as bringing hot steel to room temperature too rapidly. But it should impact the crystaline structure of steel in some way.

Mild steel does not react the same way. I can toss a yellow-hot bar of mild steel into the tub all day and not have the same hardness problem I would with high-carbon steel. Is there any particular reason that we're assuming mild-steel here? Additionally, not all steel is the same, regardless of the carbon content. Is there tungsten in it? What's the silica content? Don't know.

BaronIveagh:

pretzil:

Also, on another note, the welds on bars are already significantly weaker than the bars themselves, and already have brittle properties, freezing them would no doubt make them even easier to snap out.

Glad I'm not the only one to notice this.

And the film actually bares this out as the bars do not deform themselves but clearly break at the welds on the cross beam, as you can see in the footage.

Sorry, guys, right conclusion, wrong reasoning.

Actually, the video has him snapping the bars themselves, not just the welds.

Lightknight:

BaronIveagh:

pretzil:

Also, on another note, the welds on bars are already significantly weaker than the bars themselves, and already have brittle properties, freezing them would no doubt make them even easier to snap out.

Glad I'm not the only one to notice this.

And the film actually bares this out as the bars do not deform themselves but clearly break at the welds on the cross beam, as you can see in the footage.

Sorry, guys, right conclusion, wrong reasoning.

Actually, the video has him snapping the bars themselves, not just the welds.

Also, weld strength of steel is nearly 100% of the steel itself. It's why we weld things instead of rivet them: same strength, less weight.

delroland:
Also, weld strength of steel is nearly 100% of the steel itself. It's why we weld things instead of rivet them: same strength, less weight.

I'm not 100% sure how you can claim that. There are several forms of welding and several of them include a filler metal that may or may not be as strong as the existing material. Likewise, welds can be poorly/incompletely done and if any place on a welded metal structure is going to break it will most likely be the weld.

http://www.howstuffworks.com/welding.htm

Keep in mind that there are kinds of welding that don't use any filler, but I wouldn't expect any such process to be used on something like that. For example, I would forge weld some metals together using nothing but flux and it'd literally be like they were one piece of metal. Even then, if I left any flaw then it would be the weakness. So there is credence to saying that breaking a weld is easier than breaking a solid bar, so my objection is only with the point that the bars themselves were being shattered in the video and not just welds.

Lightknight:

delroland:
Also, weld strength of steel is nearly 100% of the steel itself. It's why we weld things instead of rivet them: same strength, less weight.

I'm not 100% sure how you can claim that. There are several forms of welding and several of them include a filler metal that may or may not be as strong as the existing material. Likewise, welds can be poorly/incompletely done and if any place on a welded metal structure is going to break it will most likely be the weld.

http://www.howstuffworks.com/welding.htm

Keep in mind that there are kinds of welding that don't use any filler, but I wouldn't expect any such process to be used on something like that. For example, I would forge weld some metals together using nothing but flux and it'd literally be like they were one piece of metal. Even then, if I left any flaw then it would be the weakness. So there is credence to saying that breaking a weld is easier than breaking a solid bar, so my objection is only with the point that the bars themselves were being shattered in the video and not just welds.

High-tech jails of the future will most likely not use bars with poor welds, especially when they have the technology to create glowing goop that drops anything it touches to absolute zero. Industrial quality welds in such a setting will be so close to the strength of the material so as to be irrelevant to the discussion.

My biggest problem with most video series on the escapist is the lack of genuine screen presence, personality and general public speaking skill that seems to persist when someone hops in front of the camera. That said, your show does NOT have any of those problems. You guys are genuinely interesting to hear speak, clear and concise as to what you are saying, very presentable and on top of all that seem very comfortable and genuine in front of the camera. Nothing you say or do feels forced, and that is really the biggest mistake most people will make when trying to be affable and entertaining, overdoing it.

Of course I'm not trying to take anything away from any of the other series on this site, as I generally watch and enjoy them all, but something about this one says "born entertainers" more than the others.

So yeah... keep up the good work.

I'd like to point out that poor quality welds have been found inside Nuclear reactors. So, no, I suspect even future prison will be built by the lowest bidder.

Secondly, a weld does not have '100% of the strength of steel' and quickly loses strength if the temperature increases of decrease too much, as the metals involved expand and contract at different rates, leading to breaks in the weld.

sirjeffofshort:
My biggest problem with most video series on the escapist is the lack of genuine screen presence, personality and general public speaking skill that seems to persist when someone hops in front of the camera. That said, your show does NOT have any of those problems. You guys are genuinely interesting to hear speak, clear and concise as to what you are saying, very presentable and on top of all that seem very comfortable and genuine in front of the camera. Nothing you say or do feels forced, and that is really the biggest mistake most people will make when trying to be affable and entertaining, overdoing it.

Of course I'm not trying to take anything away from any of the other series on this site, as I generally watch and enjoy them all, but something about this one says "born entertainers" more than the others.

So yeah... keep up the good work.

*sniff* Does.... does..... anyone have a tissue? *sniff*

SirJeffofShort, your post really made my day... thanks for the ultimate compliment. Colby and I set out to make sure we did not come across awkward or unnatural as much as we could help... although we couldn't rid ourselves of the awkward part because of who we are, I still do hope we seem natural and real. This is how we really are in real life. If you come to the Expo, you will see no difference in who we are in person versus who you see on this show. Our earlier episodes were toned back some and were certainly less natural than these later episodes... but we definitely set out to just be us on camera and I am glad you see us that way. I hope others feel the same way.

Thanks again for watching the show and for your unbelievably kind words about us and the show.

Jason Dean
REEL PHYSICS

This may be a stupid one, but how about the motorcycle dome run by Homer and Bart. Gotta be some wonky things happening between the glass and the motorcycle tires...

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