Reel Physics: The Dark Knight - Truck Flip

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You know, I always wondered why there was all that smoke coming from the truck at the moment it was flipped, now I know thanks to this video.

EvilChameleon:
You know, I always wondered why there was all that smoke coming from the truck at the moment it was flipped, now I know thanks to this video.

That's just Joker Gas... which looks a lot like steam from a piston from certain angles.

Great video guys, I had no idea this scene was even remotely possible.

Useful to know if I ever want to flip a semi welded to an empty trailer attached by super-strong cables to immovable lamp posts :)

Draconalis:
This was the first episode I just didn't like.

I don't know if it was the nature of the scene, or the call based on how ridiculous that scene actually is...

I also REALLY miss the system I understood. I don't know how much weight 10000kg is...

Can you put conversions in the description or something...?

At least I know it was 45ish miles an hour... that was one term I didn't have to ponder.

My biggest complaint about all this, since it's been two episodes in a row... is every time I hear a measurement I don't understand, I stop listening to the video and think about how much I have no idea what that translates too... which detracts from my enjoyment of the video.

This isn't going to solve the problem exactly, but it'll give you a handle if you want to convert stuff yourself : http://www.convert-me.com/en/

Weight is the easy one, 1 pound equals 0,45 kilograms (so divide by 2 and subtract 10%)

EDIT: SUBTRACT...

Considering you'd have to support all that weight, how deep in the ground would the divots from the saucers from Independence Day be?

http://www.youtube.com/watch?v=0dqirTDPMWI

Another interesting episode, well done! Very enjoyable indeed.
Also, damn those crazy cosplayers, and shame on them for doing such crazy stuff.

Eleuthera:

This isn't going to solve the problem exactly, but it'll give you a handle if you want to convert stuff yourself : http://www.convert-me.com/en/

Weight is the easy one, 1 pound equals 0,45 kilograms (so divide by 2 and subtract 10%)

EDIT: SUBTRACT...

Yeah... pausing to figure it all out would be worst than pondering what I don't know... I will keep the weight conversion in mind though, Thanks.

Anakinnnn:
This week is another viewer suggestion thrown out there for you guys. Thanks for watching... and for those of you who bail at the "end", be sure to stick around during the credits for the blooper reel. I have seen several people not even know they have been there every episode!

Thanks for supporting the show!

Jason Dean
REEL PHYSICS

Gotta say I am not enjoying everything being in metric, if I am going to have to pause to do the math mid show to convert it such as the weight of the trailer and cab or the truck as well as distances I am just really not going to bother with the show, which would be a shame because I rather enjoyed it before.

Even if you dont want to say every conversion in your explanations you could at least show the conversion on your graphics.

The out-takes are always fun.
+ Liking the metrics.

I'm not fully sure how much of this i understood, but i feel smarter already!

Thank you for such a fun educational show.

I for one am gonna hop on the european bandwagon and say that it's nice to have it in metrics! though i can ofc understand that written conversions would help loads for a lot of people.

Either way, keep on truckin!

you guys could do with some more light on ye.

I think I speak for a lot of people when I say most of us aren't verse in physics and math. The show have improved a lot by adding cgi to aid in its explanation (which I did suggested in the initial episode of the show). However it would help if some of the math concepts like can also be elaborated this way, it doesn't even have to be in the actual show, you can do it in another show (call it reel math or something) or replace the blooper which serves little with it.

intresting, mythbusters have proven that you cant TURN a car (let alone truck) with cables, but apperently you cna flip it.
The problem for mythbusters though wasnt enough energy, all cables were snapping or removing parts of car it was attacked to. so that wouldnt hold in such situation.

I hate maths. But I am so addited to your show. Good work sir's, damn good work.

Draconalis:
This was the first episode I just didn't like.

I don't know if it was the nature of the scene, or the call based on how ridiculous that scene actually is...

I also REALLY miss the system I understood. I don't know how much weight 10000kg is...

Can you put conversions in the description or something...?

At least I know it was 45ish miles an hour... that was one term I didn't have to ponder.

My biggest complaint about all this, since it's been two episodes in a row... is every time I hear a measurement I don't understand, I stop listening to the video and think about how much I have no idea what that translates too... which detracts from my enjoyment of the video.

To convert kilograms to pounds it's 2.268 pounds per kilogram. Honestly, metric is a shitton easier to use, I'd recommend familiarizing yourself with it, if not for this, then for the practicality the system offers over standard.

OT: I'm loving the series, because I do shit like this on a semi regular basis, then get fed up with the math. This way I don't have to deal with it. Unless I really want to.

I just found this series out today! I do like it. The truck flipping scene never bothered me as much as batman turning on a dime on his motorcycle after that.

If you want one to look into, the trap Will Smith gets caught in from I Am Legend has always interested me. I always feel like his leg should be ripped off when I watch it. Physics, but not the sterotypical hollywood physics.

Fayathon:

To convert kilograms to pounds it's 2.268 pounds per kilogram. Honestly, metric is a shitton easier to use, I'd recommend familiarizing yourself with it, if not for this, then for the practicality the system offers over standard.

It wouldn't be practical for me at all...

What am I going to do, convert something from pounds to grams just so I can convert them back to answer every customer's question?

We don't deal in grams in my society... it would be, in fact, very impractical.

Draconalis:

Fayathon:

To convert kilograms to pounds it's 2.268 pounds per kilogram. Honestly, metric is a shitton easier to use, I'd recommend familiarizing yourself with it, if not for this, then for the practicality the system offers over standard.

It wouldn't be practical for me at all...

What am I going to do, convert something from pounds to grams just so I can convert them back to answer every customer's question?

We don't deal in grams in my society... it would be, in fact, very impractical.

Metric isn't in common use where I live either, it's just a hell of a lot easier for me to do any calculations I need by converting first, then calculating, then converting back if needed. Besides if this country ever pulls its head out of its ass and abandons the standard system I'm happy knowing I at least understand basic conversions first.

Fayathon:

Metric isn't in common use where I live either, it's just a hell of a lot easier for me to do any calculations I need by converting first, then calculating, then converting back if needed. Besides if this country ever pulls its head out of its ass and abandons the standard system I'm happy knowing I at least understand basic conversions first.

It wont... and standard is fine. Your choice of measurement is arbitrary. No matter which system you use, you still get a figure that you understand for how long a distance is, or how much something weighs.

Sooo... this is Mythbusters without all the fun explosions?

Capatcha: it is different
Indeed it is.

I have no idea what's going on, I never took a physics class, and this made me feel incredibly stupid

Anakinnnn:
*words*

The most important question... when is the Mu Cow coming back? And will you make Mu Cow Plushies available? Because I would buy that.

I've been critical of this show before as I'm an Engineer for not being 100% clear.

First I've got to give credit for fairly clearly stating assumptions now, that's a big + in my book and covers your back on allot of things.

But the Center of Gravity stuff covered in this vid was near total bull to put it bluntly. You might have just of said, we are going to assume its a rigid cuboid and we are assuming the center of gravity at these co-ordinates x,y,z.

First of you CANNOT get the center of gravity of a vehicle without at least taking some weight measurements at, at least each axle, or better each wheel. Obviously that data is not going to be everywhere.

There's no programmatic or mathematical way to get the C of G with out having wheel loads. Should of either seen this coming and steered clear of this or just said we are assuming due to lack of available data that C of G is here.

An I know you guys state the 40% from the front is an assumption and so on but come on where's that come from thin air? The NTSHA stuff seems like a cleaver work around (surely its just for the cab though) but don't know why you guys didn't get your information from SAE (Society of Automotive Engineers) or as your using metric now BS (British Standards), all of this information would of been covered in depth by them or at least referenced so you could follow up on the proper material, more than likely one of them would of even had a paper published on truck flip over scenarios. I wouldn't have said anything if not for when the truck is on its nose you state that the old longitudinal center of gravity is now the center of gravity's height!

I mean come on your both intelligent guys is the mass now that its been rotated 90 degrees and is experiencing massive change in momentum, is not a uniform body and the gravitational constant is now acting upon the body of mass in a totally different direction. Can you really stand there and say the H of C of G is now just the old x co-ordinate?

Should of steered clear of this one, or gone to SAE/BS or got a book on vehicle dynamics out of the library for info, I mean for start there's tonnes of info out there on Height Center of gravity of automotive vehicles, I would ask having you only been using the internet if that's the case, can name at least half a dozen books that would cover it and in all of them its a pretty standardized test when one of the axles is raised and measurements taken.

Jedi-Hunter4:
*snip*

Aren't you also forgetting that the weight distribution from the wheels would affect the left or right position of the center of gravity, and that the vertical higher of the center of gravity is measure not from the ground, but from the height of the center of the wheel hub?

MowDownJoe:
The beginning made me think of this xkcd.

Yeah, me too. That made me like that part even more.

OT: I'm actually kinda surprised that this turned out to be as likely. Almost 4 times the required energy. Still if it would really look this way or work out in a real setting is still up for debate considering there's a lot of variables unaccounted for.

Anakinnnn:
This week is another viewer suggestion thrown out there for you guys. Thanks for watching... and for those of you who bail at the "end", be sure to stick around during the credits for the blooper reel. I have seen several people not even know they have been there every episode!

I said it before and I will say it again: your blooper reel seriously needs more martial arts and failed stunts. This is what we have come to expect.

Jedi-Hunter4:

*very interesting, logical, and probably correct comments snipped*

But the Center of Gravity stuff covered in this vid was near total bull to put it bluntly. You might have just of said, we are going to assume its a rigid cuboid and we are assuming the center of gravity at these co-ordinates x,y,z.

That is essentially what we did, but I prefer the term rectangular prism.

Jedi-Hunter4:

*Even more very interesting, logical, and probably correct comments snipped*

Should of steered clear of this one, or gone to SAE/BS or got a book on vehicle dynamics out of the library for info, I mean for start there's tonnes of info out there on Height Center of gravity of automotive vehicles, I would ask having you only been using the internet if that's the case, can name at least half a dozen books that would cover it and in all of them its a pretty standardized test when one of the axles is raised and measurements taken.

This seems fairly legit:
http://www.umtri.umich.edu/content/rr31_4.pdf

I like the newly introduced computer graphics to explain the physics. They do a great job. Keep it up guys, it is getting better each time

How about the truck flip in the 3rd Terminator? That was a much heavier truck with a lot 'stronger' cable.

Man, my suggestion actually made it! Huh.

Will you do a Nuking the Fridge episode?

Now i enjoy these vids. But i cant see the point of proven something thats obvious couldnt happen in real life....with out pistons. Might as well have a video disproving Wolverines claws or Superman flying.

This is an excellent and enjoyable series.

Oddly I disliked this episode, mainly because I felt the bumper holding, and the posts somehow grabbing the truck was utterly un-realistic. That part was glossed over for this episode, which I understand, but I still think if the same thing were to happen in real life, the bumper would likely just get ripped off.

Yeah, I don't know. I think a rotational approach would produce a better result.
For example, we know that this truck has an initial speed of the center of mass is 75 km/hr. When the truck begins rotating, the rope is acting on the pivot point (all it really does is keep the pivot point fixed during the rotation), so there is no torque. For the most part, the only torque is due to gravity acting on the center of mass. This causes an angular acceleration which must be overcome by the initial angular velocity of the truck in order to reach that highest point.
So the total moment of inertia is ABOUT 1120000 kg*m^2 (a few assumptions and estimations here, mostly in shapes of the truck). Initial angular velocity is about 3.34 rad/s. We know the angular displacement is pi/2 rads, because it makes a right angle with the ground. The torque due to gravity is (10000)*(9.8)*(6.24 - 1.5) * (6.24) = 2900000 N*m... maximum. The average torque is probably closer to half that, 1450000 N*m (torque changes as angle between gravity and lever arm changes). Angular acceleration is torque divided by moment of inertia, which is about 1.30 rad/s^2. Using kinematics, you get that the final angular velocity should be 2.78 rad/s... rotating back from where it came.
The problem with the energy approach is that you have those extra values (work due to sound and heat, elastic energy from the rope) that you can't really estimate and have to just kind of leave there. So even though the math says that this isn't possible, you can't really definitively say whether it's possible or not. With the rotational, you have some weird assumptions (I said the cab was a sphere, because that was the closest to the shape it actually is), but it's at least able to be estimated.
I hope this isn't just all babble that makes no scientific sense. I really enjoy physics, so I had good fun making this post. =P

saintdane05:
Man, my suggestion actually made it! Huh.

Will you do a Nuking the Fridge episode?

AHAHAHAHAHA.... Um. There is a definite possibility that there could be some sort of Hans Solo/explosion action coming up.

FinalHeart95:
Yeah, I don't know. I think a rotational approach would produce a better result.
*snip*
I hope this isn't just all babble that makes no scientific sense. I really enjoy physics, so I had good fun making this post. =P

It did make sense, and when we started the analysis I was going to approach it rotationally as well. It came down to being able to find published information on commercial truck center of gravities, and not being comfortable with trying to figure out the mass moment of inertia of an 18 wheeler without modeling the whole thing, chassis engine, etc. We made the choice to put our idealized assumptions in the strength of the bumper and cables and make an educated guess at that CoG, rather than make unsubstantiated guesses at the rotational inertia and educated guesses at the cable's moment arm.

Colby Henslee
RE-AL PHYSICS

Love this show! And love that they do most of their calculations using SI units like any physics major would.

saintdane05:
Man, my suggestion actually made it! Huh.

Will you do a Nuking the Fridge episode?

I know old Refrigerators were built strong. They used to advertise that. One had a circus elephant standing on the Fridge. I don't think it would protect you from radiation, though.

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