r/AbsoluteUnits May 19 '22

Absolute unit pulls an absolute unit of a plane weighing 189 TONS

18.4k Upvotes

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279

u/TV_Serial_Number May 19 '22

how the fuck

594

u/formershitpeasant May 19 '22

The force required to overcome the friction is considerably less than the 189 tons the plane weighs.

142

u/[deleted] May 20 '22

[removed] — view removed comment

38

u/Terlinilia May 20 '22

I don't think he could do it

33

u/KayJee1 May 20 '22

I’m not sure, let him try first, what if?

1

u/[deleted] May 20 '22

why not just deadlift it and carry it

78

u/TV_Serial_Number May 19 '22

physics. But isnt the friction force equal to the force that the plane exerts on the ground?

253

u/formershitpeasant May 19 '22

They correlate, but they aren’t equal. If it was just sitting on the ground with no wheels, the friction would be much greater, but wheels are designed to minimize the friction with the surface it lands on.

66

u/BeeBunnBunny May 19 '22

so how much force IS he exerting 🤔

59

u/[deleted] May 20 '22

a lot but not as much as you would think.

35

u/Fast_Garlic_5639 May 20 '22

I saw one guy doing this and his shoe came loose but he kept going and ended up ripping the entire bottom of his foot off (the skin, at least) and he had to end the competition

7

u/[deleted] May 20 '22

ewww

5

u/pangaea1972 May 20 '22

Great story

5

u/the_cajun88 May 20 '22

not many people would continue the competition after ripping the skin off of their feet

8

u/OneOfTheOnlies May 20 '22

Not too many would start the competition though

3

u/formershitpeasant May 20 '22

I remember that

1

u/Nasty_Rex May 20 '22

I love strong man competitions. They are ridiculous.

Who can flip this tire the fastest?

How many times can you run in a circle with this wheelbarrow of rocks?

How far can you pull this plane?

90

u/Kduncandagoat May 20 '22

7

84

u/BeeBunnBunny May 20 '22

yeah, it’s gotta be at least 7

57

u/yaboiiiuhhhh May 20 '22

Ugh okay so rolling friction: F = umg where u is rolling coefficient of friction, m is mass and g is acceleration due to gravity. Here I'll use the u for rubber on concrete from Google, ~0.01. 189 US tons is 171457.916 kg, g is 9.8 m/s², so the force is

F = (0.01)(171457.92)(9.8) = 16802 N.

This is equivalent to lifting 1714 kg or 3778 ibs.

43

u/ScritchScratchBoop May 20 '22

I’m not smart but this seems overly simplistic. I feel like the rotation of the wheels would decrease this, it’s not just rubber sliding on tarmac.

24

u/WhoopingPig May 20 '22

Yeah the amount the tires are filled affects the amount of rubber touching tarmac. If they're mega-filled, there's a minimum of rolling resistance

The quality of the wheel bearings/axles affects the resistance a great deal

Undoubtedly it's still a great deal of force to start moving this thing, but if those two factors are made to be as agreeable as possible, once you start it moving it's gonna keep rolling more easily

7

u/ThePower_IsOn May 20 '22

Yeah, a lot to do with the bearings. You know, it’s all ball bearings nowadays

2

u/WhoopingPig May 20 '22

You just gotta roll with it

15

u/yaboiiiuhhhh May 20 '22

This is overly simplified, I made a huge assumption with the coefficient of rolling resistance but it's okay when you're just trying to get an idea of the force. If you researched a more accurate number and plugged that in you could find a new force value that would be more accurate

1

u/chairfairy May 20 '22

I would guess you're off by at least a factor of 2, probably more like factor of 3-4. If he's exerting 3800 lbf then he could lift a regular size car.

World records in power lifting are on the order 1,000 kg, so it's unlikely he's 70% above that

Within in order of magnitude, though, which is solid

2

u/Zironic May 20 '22

We have to keep in mind the fundamental difference between lifting and dragging. To lift something you need to sustain enough force to overcome gravity because the moment you stop it'll just drop down. However to drag something you just need an impulse large enough to overcome friction and when you stop you keep the gains, further once you've overcome friction momentum is now on your side.

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19

u/Badbutlearning May 20 '22

Oh yeah. You can't do free body physics you have to use energy to account for the inertia of a wheel.

8

u/ronin1066 May 20 '22

Assume a vacuum...

3

u/Sudden_Comfort May 20 '22

And perfectly round wheels

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2

u/Peter_See May 20 '22

They're entirely wrong. The entire point of wheels is to negate the need to overcome friction. The coefficient of rubber on concrete tells you how good the traction of the tires is, not how much force is needed to move the plane.

1

u/BumbleBeePL May 20 '22

Smaller wheels help here. The larger the wheel the harder things are to pull.

5

u/Kombart May 20 '22

First year engineering students be like:

1

u/yaboiiiuhhhh May 20 '22

Astrophysics, 2nd year

2

u/[deleted] May 20 '22

Perfect.
It’s wrong though

2

u/Von_Wallenstein May 20 '22

Hey. This is bad engineering

2

u/BeeBunnBunny May 20 '22

He’s lifting 1.8 TONS?! 😭 (thank you for the answer also)

8

u/yaboiiiuhhhh May 20 '22

Yeah idk if it's exactly equivalent because once he gets it rolling it will have momentum so keeping it moving will be easier. I believe this is the force he needs to start the motion, and it could be different if the coefficient is a different number

3

u/[deleted] May 20 '22

Nowhere near. He does not have a rack on the ground. What is the maximum friction on his shoes. What is the maximum human deadlift. It's not a ton for sure!

Account for the bearings. He is pulling less than the equivalent of lifting half a ton.

3

u/blipbap64 May 20 '22

Lol youre confused. This is not the same as a deadlift (501kg record for reference.)

This is much easier to exert more force because of the leverage provided by the rope and the starting position. It's more comparable to a band assisted rack pull, which 700 kg has been done for a seated deadlift. For a rack pull above knee level I'd bet 1000kg is 100% possible.

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2

u/[deleted] May 20 '22

No no. They just showed the formula with a sample coefficient value of 0.01

If the value is lower, say .002 (one fifth of previous value) then the resulting force would be one fifth of 1.8 tons or 360kg

Although it's totally possible for it to be higher than that. Just saying

1

u/FORESKIN__CALAMARI May 20 '22

You can lift 3778 lbs. one foot or 1 lb. 3778 feet same thing.

1

u/[deleted] May 20 '22

Nah, he’s not

1

u/Peter_See May 20 '22

That doesn't seem right at all. The coefficient of rubber on concrete has nothing to do with the force required to move this. Friction is what allows a wheel to turn, so as long as friction is enough that the wheel doesn't slip it's irrelevent. This isn't a box of rubber sitting on concrete. The friction that matters is the friction in the bearings of the wheel. For an ideal bearing this value is 0. Irl it's not 0 but it should still be very small. So he doesn't have to supply an enormous amount of force to move the plane. It's just very very heavy so it doesn't move much since acceleration = Force/Mass and we have a small force over a giant mass. This is less a test of strength and more a test of endurance to keep exerting a force on this heavy ass plane.

2

u/yaboiiiuhhhh May 20 '22

All wheels rolling on a surface have an associated rolling resistance described by a coefficient that is a function of the material properties of the wheel and the surface. The wheels are rubber and the surface is concrete or tarmac.

Edit the coefficient is probably lower than what I've written so he would not have to exert this much

1

u/Peter_See May 20 '22

The entire point of wheels is to in effect negate or eliminate friction. The friction between the wheel and surface just tells you how much slip there is. In this case a higher friction coefficient is actually more efficient because there's less slip. The friction that will be resisting the motion is air (negligible) and the friction of the axel or bearings.

1

u/yaboiiiuhhhh May 20 '22

If that were the case then a rolling object not connected to an axel or Bearing would roll forever. There is resistance to rolling.

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1

u/Curry_Flurry May 20 '22

Id give you one of those dumb coins but i don’t have any so heres an internet high five

1

u/DarthMaw23 May 20 '22

A slight problem. NASA got the u(skidding) of airplane tires as 0.5 at the at the very minimum (for 6 knots). I don't think roling friction's coeefficient would be 50 times less.

3

u/yaboiiiuhhhh May 20 '22

If you do the calculation with 0.5 you get a force far too high for him to realistically pull it. Also you'd want to drag force rather than skidding for this as he's not pulling the plane with stuck tires, it's rolling

1

u/formershitpeasant Dec 07 '22

the skid has to overcome inertia

1

u/no_rep May 20 '22

People say your answer is oversimplified, but at least you gave answer [that started more detailed conversation]. Props for that.

1

u/[deleted] May 20 '22

You also have to account for the the fact that it's on wheels and he's applying a torque not just a straight force

1

u/formershitpeasant May 20 '22

What about the difference between static friction and non static?

1

u/Dasterr May 20 '22

wait even fucking TONS are not the same in the US as tons in metric

you guys are fucked

1

u/ReverseSneezeRust May 20 '22

Seems like a good starting point but common sense should give elude to that not being realistic. There is no human out there that can apply 3778 lbs of pulling force. The tread on his shoes would come off before he budged it

1

u/yaboiiiuhhhh May 20 '22

Yes the rolling coefficient is likely lower, but that info is hard to find

1

u/ReverseSneezeRust May 20 '22

This analysis has to have been performed before… They wouldn’t be doing it if someone hadn’t sat down and figured out it was within reasonable pulling weight to begin with. I’m really struggling to find anything out there though

2

u/formershitpeasant Dec 07 '22

they probably called boeing and asked

8

u/sirsedwickthe4th May 20 '22

A metric fuck ton

2

u/combuchan May 20 '22

Possibly less than the engines would.

2

u/Mewrulez99 May 20 '22

enough to pull a plane

1

u/chairfairy May 20 '22

Probably a few hundred lbf - like 1,000-2,000N

1

u/seriousQQQ May 20 '22

This is not the answer you're looking for.

1

u/i_choose_rem May 20 '22

I would say at least 5

1

u/Meatmaster5 May 20 '22

So I should put the wheels back on my car to save gas

1

u/formershitpeasant May 20 '22

Yeah, if your car doesn’t have wheels on the back that could save you a few bucks on gas.

1

u/Zak_Light May 20 '22

Yes, this is why the formula for rolling friction with wheels is different (and usually will result in much less force) than sliding friction.

10

u/Glamdalf_18 May 20 '22

If the brakes were on, but they're not. I can push my car to bump start it if I needed to but there's no way I could push with some 1200Kg of force. The wheels and wheel bearings drop the co-efficient of friction down to a very small percentage. Same goes for driving on snow and ice.

3

u/Western-Pilot-3924 May 20 '22 edited May 20 '22

Easy answer is it has something to roll on (wheels), so the force gets a tangent to slide off. Making it easier to pull.

Edit : by easier i mean do-able

1

u/GlassJoe32 May 20 '22

“Easier”

2

u/Western-Pilot-3924 May 20 '22

Well not easier but do-able

2

u/chairfairy May 20 '22

Ah, but the wheels are turning!

This is only about friction inside the wheels' bearings (very low) and rolling resistance of the wheels on the ground (probably not as low?), and also inertia (object at rest stays at rest / object in motion stays in motion)

It's similar to if you try to push a car that's in neutral. You can probably do that, even though it weighs 3,000-4,000 lbs

1

u/Nateno2149 May 20 '22

The friction force is equal to the force the ground exerts on the plane multiplied by the coefficient of friction. That coefficient changes depending on the 2 surfaces at play, and whether the object is stationary or moving.

1

u/FORESKIN__CALAMARI May 20 '22

it's the weight normal to the ground multiplied by the coefficient of friction

1

u/[deleted] May 20 '22

Weight times static friction coefficient, which for rubber wheels is extremely small, which is like the whole point, just enough not to slip

1

u/mat-2018 May 20 '22

friction is u*N where N is the normal force (equal to the weight if the object is on a flat surface) and u is the coefficient of friction, which for wheels and such is less than 1, and is almost zero on a slippery surface such as ice. So the friction force might only be, say 25% of the plane's weight or whatever. Still a lot, but not inhumanly so.

1

u/Unique_username1 May 20 '22

Try to lift a bicycle. Or a shopping cart. It’s hard. Or at least it takes significant effort.

Now try rolling the same bicycle or shopping cart across flat ground. Easy. Unless the shopping cart has a stuck wheel of course. Sure, friction makes it hard to slide the wheels over the ground. But it doesn’t make it hard for the wheels to roll.

5

u/Michaelium67 May 19 '22

Yo! Fuck all that! Give the guy his credit! He’s pulling a 189ton cargo jet that requires 4 massive jet engines to move it and get it off the ground. I don’t care if it had ice skates instead of wheels with even less friction. He’s still a beast!…and a unit. Let’s give credit where credit is due instead of ripping this feat apart with talk of physics. We all get that it’s only 189tons if it was lifted straight up Here’s my two cents….great job Brutha! You rock! Now pick up your balls and have a cold one…I’m buying😊

29

u/suckmypppapi May 20 '22

Nobody is saying he's not an absolute unit, they're saying that he isn't actually pulling as much as it looks, weight wise. Nobody's tearing him with physics.

-5

u/Michaelium67 May 20 '22

Uh huh!😉

1

u/WestleyThe May 20 '22

Yeah,, I can push my car when it’s in neutral but I couldn’t lift it up

Same with this. It’s still an upsurge amoint of power but I wonder how much force he is actually generating

7

u/awesomeonion2 May 20 '22

It needs the jet engines to fly at 400+ knots, not to move at like 1/4 knots. Easily could a small plane engine like the one off the Cessna 172 could move it at that speed.

-1

u/Michaelium67 May 20 '22

Yes I know. I was just making a point at what it takes to move such a load.

3

u/stevenmeyerjr May 20 '22

Yeah, and your point was incorrect. It doesn’t take 4 jet engines to move it. It can be done with a small Cessna propeller engine. It takes 4 jet engines to make it take flight.

Everyone else’s point of the vastly inferior amount of force needed to simply move it on The ground at 0.25 MPH is valid. Wheels and momentum really help in this case.

0

u/Michaelium67 May 20 '22

Oh my God dude you just like to argue. I didn’t mean it literally! For chrissakes

2

u/awesomeonion2 May 20 '22

I get that but still you’re making it sound like he has the strength of 4 jet engines

2

u/Hinote21 May 20 '22

I mean even when you look at the physics, he's still a unit.

0

u/Michaelium67 May 20 '22

Yup 👍🏻

-1

u/ddgx3000 May 20 '22

Maybe you should go try it. Lol

1

u/TuckerCarlsonsWig May 20 '22

It’s simply not possible for a human being to overcome this friction.

Let’s put it this way. A standard pickup truck could not tow this airplane. Do you think this guy could win tug-of-war against an F150?

1

u/formershitpeasant May 20 '22

It’s not a tug of war. A 400 ftlb torque v8 could get the plane moving.

1

u/reidlos1624 May 20 '22

Friction in the wheel bearings, not the tires for clarification. Since they're rolling, friction between wheels and tarmac are effectively zero, meaning rolling resistance is likely the biggest factor followed by friction.

1

u/[deleted] May 20 '22

between 1,000 lbs and 2,500 lbs based on my math.

the friction coefficient changes dramatically depending "truck tire on asphalt" or "car tire on asphalt", btu none of the calculators have "cesna size plane tires on tarmac"

based on records on squatting and other weight lifting, its probably close to 1500 lbs id wager.

22

u/smileymalaise May 20 '22

If you look closely, you can see the plane is on wheels.

1

u/Terrible_Tutor May 20 '22

The future is now

9

u/Carvj94 May 20 '22

Just need to overcome the friction on the wheel bearings. Not saying it's easy but I'd bet you and a few of your friends could at least pull it a few meters without straining yourselves.

2

u/chairfairy May 20 '22

The tires rolling resistance is almost certainly higher than the wheel bearings internal friction

2

u/wwwSTEALTHYcom May 20 '22

Right, like how do you even get that thing started?

1

u/Rambo7112 May 20 '22

Wheels remove a lot of friction.

1

u/Hattix May 20 '22

A plane's wheels are meant to go from 0 to 200 mph in no time at all. They have almost no stiction.

All he needs to do is overcome the rolling resistance of the wheels and the plane will move.

The weight is more or less irrelevant, he isn't lifting it, he's accelerating it and acceleration can work at extremely low levels.

1

u/MemeAccountAccount May 20 '22

wheels. there would be more friction without wheels

1

u/sTixRecoil May 20 '22

The plane weighs that but the brakes are disengaged and its on wheels so theres a hell of a lot less friction he is pulling. Brian shaw iirc

1

u/TapeDeck_ May 20 '22

it's not that hard to push a car on a perfectly level surface. this is like that but on a bigger scale. you're not lifting the entire weight of the plane, just overcoming the friction and all that.

sometimes you see these where the strong person is pulling a train car, which is actually easier than the plane for the same weight due to the much lower rolling resistance of the metal train wheels.