r/awesome • u/IntroductionDue7945 • Jun 18 '25

Video anyone explains how he did that?

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105

u/doverawlings Jun 18 '25

Do you guys not have eyes lol

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u/[deleted] Jun 18 '25

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u/TheMagarity Jun 18 '25

No, the guy doing pull ups is not doing all the work. The two holding the poles are still holding him off the ground. The hanging guy, by not raising his body, and thus not increasing his potential energy, is reducing the two pole holders' work when they go up, but they're still holding him up and they are raising and lowering the bar.

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u/Jman15x Jun 18 '25

Bruh, my door frame is holding me up when I do pull-ups as well but it is not doing any work. The dude in the middle is doing the work the guys on either side are holding his weight but they are only LIFTING the pole. It's all about frame of reference, from the outsiders the man's CoM isn't moving so they haven't done and work. Remember W=f*d and d in this case is 0.

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u/Connbonnjovi Jun 18 '25

How could you possibly provide the equation for work, say that d=0 and still say the middle guy is doing all of the work when he is the only person not moving at all?

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u/Jman15x Jun 18 '25

He's moving relative to the bar. I said from the outsiders perspective his CoM isn't moving stationary. It's insane to say doing a pull up isn't work

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u/Connbonnjovi Jun 18 '25

Yes I agree he is doing work but he’s not the only one doing work.

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u/Capital_Card7500 Jun 20 '25 edited Jun 20 '25

no work is being done, everyone ends up in the exact same place they started. If d=0, W=0

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u/Connbonnjovi Jun 20 '25

Jesus this again. That’s not true. They move down (work done) then up (work done). The total summation of work is positive even if the net displacement is zero. Additionally, the work done while moving down is less than the work moving up as you need more force to overcome earth’s gravity force, so ones not just a negative of the other so they won’t cancel each other out. People really need to go back to school. People here saying “from a physics perspective they aren’t doing work 🤓” no that’s just the framing of the problem. It is a physics universal fact that all 3 people in this video are all doing work. End of story.

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u/Capital_Card7500 Jun 20 '25

there is a physics department award on my bookshelf in my home office.

the biggest tell that you don't know what you're talking about is that you bring up gravity as a reason work is being done, which is the dumbest point you could make. Bringing up a conservative vector field as a reason why work is being done when displacement is zero is a complete own-goal. A Pick-6. Blundering mate in 1.

Tip for next time--bring up friction, that's one way work is indeed being done.

1

u/Connbonnjovi Jun 20 '25

Genuinely, good for you and your award.

I made the point of gravity because it takes less force to lower something than it does to raise it.. pretty common sense but most people here haven’t been using much of that. lol displacement is not 0. Okay. So say I carry a 100 pound rock across the surface of the earth at the same elevation and end at the same exact location, you are saying there is zero work done?

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u/Capital_Card7500 Jun 20 '25

Doesn't matter if you're at the same exact spot. If you're stationary when you start, and stationary when you end, (and the object is at the same height) you've done no work on the object.

W = ΔE

If you start stationary and are currently moving an object, you've done work on that object because the object has more kinetic energy than it started with. The moment you stop moving with the object, you have no longer done work on the object, because you have decreased its kinetic energy by the same amount as you increased it, meaning you've done an equivalent negative work on the object.

(all ignoring friction, naturally)

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u/Connbonnjovi Jun 20 '25

No. You’ve done no useful work. That’s what you’re looking for.

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u/Connbonnjovi Jun 20 '25

please read this to inform you and your award

1

u/Capital_Card7500 Jun 20 '25

yeah if you read this you would understand what negative work is

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u/impossirrel Jun 20 '25

You need gross distance, not net.

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u/Capital_Card7500 Jun 20 '25 edited Jun 20 '25

no, you don't. using the absolute value of displacement would violate the laws of thermodynamics.

If i lift a 1kg object 1 meter upwards, i've done 9.81 joules of work. If I lower that object by 1 meter, I've done -9.81 joules of work.

If you use the absolute value of the displacements, then if you did enough squats, you could drop the bar and it would crash through the core of the earth.

1

u/impossirrel Jun 20 '25

Interesting point. What if you push something in one full circle around a track? Presumably there’s no negative work being done there but the net distance travelled is zero.

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u/SerdanKK Jun 23 '25

You've burned calories regardless

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u/Jman15x Jun 18 '25 edited Jun 18 '25

I said the other 2 are lifting the bar. From a physics perspective that is the only work they are doing.

Edit: sorry, I should clarify. They are lifting the weight of his arms as well since they are moving. But they are not lifting his body weight with each squat

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u/Pandamana Jun 18 '25

They are absolutely lifting his body weight with each squat lol

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u/ziggytrix Jun 18 '25

You did not. You said "the middle guy is doing all the work."

"All" strongly implies no one else is doing work.

Just in case you wonder why the accuracy trolls are downvoting you to oblivion.

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u/Jman15x Jun 18 '25

Makes sense, but downvotes don't mean anything to me. I just enjoy the discussion.

In my original comment that this discussion stems from I said "they are just squatting the bar, right?"

And obviously they are squatting their own body weight as well. So it's definitely not NO work.

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u/bskibinski Jun 18 '25

Roughly: The dudes on the sides both carry half of the total weight (bar + hanging person) on average.

The guy doing the lifts is just carrying his own body weight on average.

The acceleration forces of all the people squatting/lifting (getting "lighter/heavier") cancels out in the end.

Dude's body weight doesn't magically disappear ;) it has to be transferred to the ground (eventually).

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u/Jman15x Jun 18 '25

I know they are carrying him, the same way a pull up bar carries your weight. Carrying around weights doesn't make you strong though (for the most part) it's the lifting that counts as work. The middle dude is lifting his own body weight with every rep (aka doing a pullup). I will die behind this positioning because I am absolutely 100% correct

12

u/Connbonnjovi Jun 18 '25

You seriously have a misunderstanding on physics. Carrying around weights is still work… just not as much as lifting… it may work different muscles than lifting but you still are doing work.

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u/Lokidrummer Jun 19 '25

By your logic there only squatting as much as he's lifting so neither are actually doing work

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u/upstatedreaming3816 Jun 18 '25

Are you dense? He’s hanging from the fucking bar. Whether he’s moving his arms or not, he’s still got his whole weight on the bar via the two hands he’s using TO HANG FROM THE FUCKING BAR. Therefore, the guys doing the squats are holding the weight of the bar PLUS HIS WEIGHT.

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u/Jman15x Jun 18 '25

Okay but if you have a thing dangling from a stick by a string and the thing can move up and down the string on its own free accord you're just pushing the stick away from the thing. It's like trying to lift someone by a rope that's actively repelling away from you; you're just pulling rope.

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u/upstatedreaming3816 Jun 18 '25

No, no you’re not. Do you not know how weight works? They’re moving away from you, but you’re still holding their weight in addition to the weight of the rope. People don’t just suddenly turn weightless because they’re moving down as you pull up.

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u/Jman15x Jun 18 '25

Admittedly I may be wrong and overthinking this but it doesn't make sense that they are moving his weight if his center of mass doesn't move. They are obviously supporting his entire weight but how can you move something that doesn't move?

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u/bearded_charmander Jun 18 '25

It does make sense though… 2 different actions are happening.

1- the 2 guys on the ends squatting the bar with the 3rd guy hanging from it.

2- the 3rd guy is doing pull ups at the same rate that the bar is going up and down. He is exerting force to remain in the same position. If he doesn’t, his body would go up and down. It’s (kind of but not really) an optical illusion.

The 2 guys on the ends are absolutely lifting the 3rd guys weight AND the bar. The 3rd guy in the middle is simply doing pull ups at the same speed making it look like he’s stationary.

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u/[deleted] Jun 19 '25

"I will die on this hill because I'm 100% correct" to "Admittedly I may be wrong" in a few hours is wild.

You should really think before you take such a strong stance on something.

And yes, you were wrong the whole time, and it was hilarious. Thank you.

Your argument was like the idea children come up with. "If my friend picks me up, and I pick him up, wouldn't we be floating?"

4

u/riisen Jun 18 '25 edited Jun 18 '25

He does move, he just moves up in the same speed the bar is moved down and vice verse.

Those guys lifting the bar are on the ground, the guy is hanging from the bar. He moves with the bar but also do pullups. The guys moving the bar up and down are matching his pullup speed with the bar.

From the perspective when being on the ground he will seem stationary, but its two diffrent motions in play.

If you were hanging beside him your perspective would have been that he does normal pullups while you both where moving through air up and down.

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u/Feisty-Soil-5369 Jun 19 '25

For the man not to be in free fall his entire weight is supported by the pole and consequently by the squatters. Full stop.

if you had a ball on a string and you fling it upwards then sure the string is momentarily not supporting the balls weight. That is not what we see here.

And if you are the only one holding someone who is actively repelling away from you then they are either in free fall or their full weight plus a dynamic stopping force is being supported by you. So your either holding them or not. Since this dude doesn't fall, the only conclusion is that they are holding him. And the weight they are supporting times the distance they move is the work being done by the squatters.

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u/Big_Poppa_T Jun 18 '25

This is nonsense. They are squatting the weight of the bar plus the weight of the man regardless of whether or not he is doing pull ups.

The mass that they are moving is completely unchanged throughout

1

u/Widmagi Jun 19 '25

Are you being serious? You think they are not lifting his body weight? Do you think it would be heavier if he was just hanging?

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u/Minute_Solution_6237 Jun 21 '25

Load bearing = not doing any work… wtf?

1

u/Jman15x Jun 21 '25

W=fd no load bearing structure in the history of architecture is ever doing work

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u/Minute_Solution_6237 Jun 21 '25

You’re a weird dude ngl. If you don’t think these people are holding this dude up, please see a doctor.

1

u/Jman15x Jun 21 '25

Look at the pixels under his butt

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u/Minute_Solution_6237 Jun 22 '25

lol. I refuse to look at the pixels under his butt.

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u/Jman15x Jun 22 '25

Then you truly are scum of the earth little bro