Reel Physics: Skyfall - Bonded Train Cars

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LadyRhian:

pretzil:
'Roof Railings', what do you mean by that? 1stly, the footage doesn't appear to show any steel in the roof of a rail car..

I think they mean the thin(ish) metal bars you see running parallel to the roof in the clip. As for the rest, well, it was REEL Physics after all. They wanted to make it look cool for the Cameras.

Huh? How does that make sense? Those metal bars are obviously not structural, and not even responsible for taking any load from the digger.

"It was REEL physics after all"
They determined that it was REEL because they thought in REAL life it would have stayed connected, their entire analysis was based on the assumptions that the digger was already attached when the hitch was shot out (equal in velocity), and that the passenger rail car was made of steel... Both of which are obviously not correct based on the footage in question.

Fair enough that they said that the country in question actually has modern rail systems, so that type of carriage wouldnt actually be used, but this is not REEL/REAL Geographical Facts, the PHYSICS needs to be applied to the information given in the film, with assumptions made which fill in the gaps without contradiction by the footage.

Hypothetical: If reel physics does an episode where they determine if a Chevy truck could really drive onto the roof of the Sydney Opera house, their reasoning for it being REEL physics cannot be that they don't sell Chevys in Australia...

I doubt I will ever forget the drag coefficient of a brick in my entire life.

What bothered me most about this scene was that the passenger seats are all facing backwards so they can see James Bond makes his entrance. Also everyone just calmly sitting there even after something crashes in and starts ripping off the roof.

pretzil:
'Roof Railings', what do you mean by that? 1stly, the footage doesn't appear to show any steel in the roof of a rail car.

Passenger rail cars need to be light weight, and the one in the footage appears to be no exception (steel is HEAVY), the roof structure is clearly made up of non metallic panel board sections with some kind of thin metal sheeting for outer skins.

The failure mechanism of the roof structure is clearly brittle fracture (as shown by the gash through the roof rather than any bending or stretching) with the yield/buckling failure of the metallic outer skin. As they mentioned last week, steel (at room temp) yields, and there is no sign of any yielding in the footage, which would be shown by a bar being stretched back through the cabin.

Thats my main engineering gripes with this episode.
Now for the physics part. ACCELERATION force was NEGLECTED! As soon as the train carriages were disconnected, the locomotive, under reduced load, would begin to accelerate away, even if not by much, a small change in velocity at bond's end, with the immense weight of the excavator, cars and carriage would impart even more force when he tries to grab on.

Q: "Wait, so I could push a rail car?"
A: Not from rest, but if one was already moving, and all you were doing was maintaining its current velocity, theoretically you might have enough strength.

Thank you. You kept me from having to post pretty much the same thing.

pretzil:

LadyRhian:

pretzil:
'Roof Railings', what do you mean by that? 1stly, the footage doesn't appear to show any steel in the roof of a rail car..

I think they mean the thin(ish) metal bars you see running parallel to the roof in the clip. As for the rest, well, it was REEL Physics after all. They wanted to make it look cool for the Cameras.

Huh? How does that make sense? Those metal bars are obviously not structural, and not even responsible for taking any load from the digger.

"It was REEL physics after all"
They determined that it was REEL because they thought in REAL life it would have stayed connected, their entire analysis was based on the assumptions that the digger was already attached when the hitch was shot out (equal in velocity), and that the passenger rail car was made of steel... Both of which are obviously not correct based on the footage in question.

Fair enough that they said that the country in question actually has modern rail systems, so that type of carriage wouldnt actually be used, but this is not REEL/REAL Geographical Facts, the PHYSICS needs to be applied to the information given in the film, with assumptions made which fill in the gaps without contradiction by the footage.

Hypothetical: If reel physics does an episode where they determine if a Chevy truck could really drive onto the roof of the Sydney Opera house, their reasoning for it being REEL physics cannot be that they don't sell Chevys in Australia...

Thanks again.

synobal:
Also everyone just calmly sitting there even after something crashes in and starts ripping off the roof.

The further you go east or south in Europe the less efs people give about weird stuff happening around them. Or to go Blade Runner on you: I've seen things you people wouldn't believe. ;)

Bonded Train Cars, oh, I see what you did there. :)

Wish math and physics education were better in highschool, so I didn't end up hating it although I'm a sci-fi fan. :(

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