I What is the minimum force required to lift an object?

[malawi_glenn]

Go to YouTube and search for "weightlifting fails"

I hope my videos do not show up, would be embarrassing

If I put a 60kg 2m×0.5m rock on you do you think it would hurt?

The spatial size of the rock is irrelavant, what matters is the area of contact. It will be pretty hard to find a rock with 60 kg mass which has a flat side with dimensions 2m x 0.5m

Of course the top surface of a supine human is not flat and some points will suffer a higher pressure, so I'd expect it to be uncomfortable (rather like lying face down on flat concrete is, in fact) but hardly fatal.

 

[Orodruin]

videos of idiots benchpressing too much without a spotter and ending up trapped under their barbells' bars

Don’t look at the squat fails if you don’t want to scream in empathy pain…

The bottom line though is that the OP is trying to equate experienced sensation to physical measurement. This is of course bound to fail because sensation depends on so much more - as already pointed out repeatedly. The OP won’t learn anything by stubbornly refusing to accept the shortcomings of their approach.

A very small force is enough to kill a human if applied appropriately - like at the tip of a knife. The same force spread evenly over the body, not so much.

 

[Ibix]

The spatial size of the rock is irrelavant, what matters is the area of contact. It will be pretty hard to find a rock with 60 kg mass which has a flat side with dimensions 2m x 0.5m

Well, you could get one cut. As I noted upthread it would be only a centimeter or two thick, so actually pretty fragile and would need careful handling.

I suspect that's why the OP has now switched to talking about 18cm × 18cm rocks (about the same size as a pair of human feet): he wants to compare to someone standing on your stomach. Neither experience would be particularly comfortable, I think, but neither would crush you to a pulp.

I hope my videos do not show up, would be embarrassing

I'm going to google "malawi_glenn weightlifting fails" now...

Don’t look at the squat fails if you don’t want to scream in empathy pain…

I'll bear that in mind...

A very small force is enough to kill a human if applied appropriately - like at the tip of a knife.

The button on the tip of a sport fencing sword should trigger if held vertically with a 200g weight on top (you can get cylindrical weights with a coaxial hole drilled for testing). According to official fencing rules that's all the force you need to stab someone with a pointed weapon.

 

[Orodruin]

According to official fencing rules that's all the force

Do the official rules specify standard gravity?

 

[Ibix]

Do the official rules specify standard gravity?

I don't know, actually. As long as everyone's swords are tested at the same altitude for a given competition nobody has an advantage, though.

Actually, I think I have it wrong. The button shouldn't trigger with a 200g weight, but may trigger with a 200+$\epsilon$ gram weight.

 

[Orodruin]

I'm going to google "malawi_glenn weightlifting fails" now...
I'll bear that in mind...

Things not to search for on youtube:
”Squat fail knee”
”Deadlift fail biceps” (what? Not supposed to try to biceps curl 300+ kg??)

 

[Orodruin]

I hope my videos do not show up, would be embarrassing

So you do have fail videos!

The big question of course becomes: What is your powerlift total and how much did you put on the bar when you failed?

 

[Yahya Sharif]

The bottom line though is that the OP is trying to equate experienced sensation to physical measurement.

In post #88 I used the idea of measuring by damage to the body not sensation. Damage to the body can be a physical measurement. It is whether the rock damage the belly or not.
The rock of 60 kg on belly area 18 cm length and 18 cm width will extremely damage the belly. A human lying on belly on a protrusion on the ground of 18 cm length and 18 cm width will only cause some pain"no damage"

A very small force is enough to kill a human if applied appropriately - like at the tip of a knife. The same force spread evenly over the body, not so much.

Yes, a knife with small force will kill a human.This is because the tip of the knife is of very small area. The area of the rock on the belly is exactly the belly dimensions 18 cm length and 18 cm width which is bigger. So the rock will give smaller damage than the knife because the area of the rock is bigger.

Eh, no it won't crush your belly...

Can you dare and put a rock of 60 kg on your belly?

 

[malawi_glenn]

Can you dare and put a 60 kg rock on your belly?

Yes.

Why do you think it is something special about rocks?


nice hollywood special effects, right?

 

[Orodruin]

In post #88 I used the idea of measuring by damage to the body not sensation.

Which, as has also been pointed out, is a very poor alternative because that is even more dependent on how the force is applied. You are only digging your hole deeper and deeper.

The rock of 60 kg on belly area 18 cm length and 18 cm width will extremely damage the belly.

No, it will not. Stop making things up.

The heaviest deadlift on record is 501 kg. By your argumentation this should have ripped the guy’s arms off.

Yes, a knife with small force will kill a human.This is because the tip of the knife is of very small area. The area of the rock on the belly is exactly the belly dimensions 18 cm length and 18 cm width which is bigger. So the rock will give smaller damage than the knife because the area of the rock is bigger.

Exactly. So you first say to use damage as a measurement and in the next sentence agree that damage is highly dependent on mode of application. Now you are just being inconsistent. That won’t do.

 

[Ibix]

The rock of 60 kg on belly area 18 cm length and 18 cm width will extremely damage the belly

60kg on that area is about 18.5kPa. A 10kg weight on a 7cm×7cm contact patch is about 20kPa.

I can report I'm still alive. I don't have more weights to hand to test more.

Edit: my twelve year old has sat on my stomach in the past, though, and he's about 40kg. I'm still alive.

 

[malawi_glenn]

So you do have fail videos!

The big question of course becomes: What is your powerlift total and how much did you put on the bar when you failed?

I have removed all my training and competition videos long time ago but perhaps some are still around on the dark side of internet.

I used to have one video where I front squated and broke my lower rib. The lifting belt I was using was causing this. When the rib was healed, I never front squated with belt again. That video was not so dramatic however.

I also had a video which I did for a friend during a strongman competition during the log press event. That poor guy broke some teeth when he was going to take the log down to his chest for the next repetition.

Never competed in strongman but I did train some. It was more about me infiltrating the powerlifting club and trying to convince them to train strongman with us instead. Because I was into strongman the only powerlifting event that I did serious practice in was the deadlift. My max there is 250 kg. No suit, just a thin belt (never used thick belts again after the front squat accident). I was pretty pleased with that lift. I could probably have done 260 kg at some point since I did 4 reps on 240 kg which is kinda where I "peaked".

Nowadays, I mostly train "bodybuilding" style and "functional strength" (I know, very sissy). I also do regular jogging. This week 3 times. The heart is the most important muscle and should not be ignored.

If the OP want to train his belly, I can recommend some excerises for him. We used to do the plank (not the Planck) which we placed a big tractor tire on our backs. I had one video where there was two girls sitting on my back instead of the tractor tire. It was pretty difficult, not because of the weight but becasue they were laughing and moving all the time. So lesson learned: tractor tire > girls.

The heaviest deadlift on record is 501 kg. By your argumentation this should have ripped the guy’s arms off.

did he or someone else do 501 kg at some point? Or did they misscalculated the weight?

 

[malawi_glenn]

Edit: my twelve year old has sat on my stomach in the past, though, and he's about 40kg. I'm still alive.

We have 60 kg dumbells on my gym. I can put one on my belly and post picture tomorrow (If I survive).

Here is a guy performing hip thrusters with 100kg barbell. The contact area is about 200 cm² which results in pressure ~ 50 kPa

perhaps those are actually green plates (10kg) which he painted blue and wrote "20kg" on? And use a "womens" barbell (15kg). That would make the total weight equate to 55kg. Or, this is also the case of some serious hollywooding.

 

[Orodruin]

did he or someone else do 501 kg at some point? Or did they misscalculated the weight?

Hafthor.


Disputable record since it was not in competition, but what are you going to do if you peak and there is a pandemic?

Because I was into strongman the only powerlifting event that I did serious practice in was the deadlift. My max there is 250 kg.

That’s pretty respectable. It is about what the strongest guy in our gym at work (”förbättrad fysik”) did before the university decided it was not supposed to run a gym and dismantled it (bad decision if you ask me, it was the typical watering hole where people from different fields would meet and talk - it probably resulted in more cross discuplinary papers than any seminar series). We also had a guy at the gym that ended up 3rd (iirc) in his class (60 years +, -93 kg) in the powerlift world championship a couple of years ago.

My deadlift PB ended up at 190 kg. I could probably have reached 200 kg at some point but life and injury intervened. Was still pretty happy with that at almost 40.

Oh, and my squat PB is 170 kg. The contact area should be about the same as for the hip thrusts above. I guess my shoulders are broken … (they are not)

 

[malawi_glenn]

Hafthor.

I still think Eddie Halls lift is more impressive, but that is not what deadlift is about!

My deadlift PB ended up at 190 kg. I could probably have reached 200 kg at some point but life and injury intervened. Was still pretty happy with that at almost 40.

Yeah that is good. And there is no point for a mere mortal to lift very heavy during a short period in their lives when the risk of injury is great. Better to train to improve your life and well being as a whole.

did before the university decided it was not supposed to run a gym and dismantled it (bad decision if you ask me, it was the typical watering hole where people from different fields would meet and talk - it probably resulted in more cross discuplinary papers than any seminar series).

I used to be in charge of a student gym. Most of the guys training there was either studying physics or civil engineering. We had a huge whiteboard there which we used to scrabble equations on between sets. I remember I helped a guy with some general relativity homework at the gym. He gave me a bottle of nice olive oil as thanks.

 

[Orodruin]

And there is no point for a mere mortal to lift very heavy

What about having undergrads start a rumor that you will only allow TA’s that bench at least 100 kg in your courses?

Edit: The TAs were more than happy to fuel this rumor …

 

[malawi_glenn]

What about having undergrads start a rumor that you will only allow TA’s that bench at least 100 kg in your courses?

Edit: The TAs were more than happy to fuel this rumor …

I don't have the luxury of having TAs :(

 

[Yahya Sharif]

Can you dare and put a rock of 60 kg on your belly?

Yes.

Why do you think it is something special about rocks?

The load in the video is on the chest which is much stronger than a belly.

Edit: my twelve year old has sat on my stomach in the past, though, and he's about 40kg. I'm still alive.

I'm not sure about a human standing on another human but if you use a rock the belly will damage severely.

The heaviest deadlift on record is 501 kg. By your argumentation this should have ripped the guy’s arms off.

Not necessarily. The arms and joints are much stronger than the belly.

 

[Yahya Sharif]

My weight is 59 kg. The video shows me lying on a block of 18.5 cm width, the block is 100% on the belly does not cover the chest.

I was able to bare it for 1 minute without belly damage. In contrary, a rock of 60 kg put on the belly* will crush the belly immediately.

*A rock of 60 has a big volume. An alternative is two loads are fixed on both ends of a bar, 30 kg for each end. Then putting a piece of wood of 18.5 cm width on the belly finally putting the bar on the piece of wood. The piece of wood and the block in my experiment are of the same width 18.5 cm, this is to create an equivalent pressure in both cases. In both cases the width is the block width 18.5 cm and the length is the belly length.

 

[malawi_glenn]

My weight is 59 kg

Hit the gym bro! Get some strong abz :)

60 kg dumbell on my hairy belly tomorrow! Very small area too. Hope I survive

In contrary, a rock of 60 kg put on the belly* will crush the belly immediately.

No. I gave you evidence with that 100 kg barbell. Provide a reference for that insane statement or stop trolling

 

[Ibix]

I'm not sure about a human standing on another human but if you use a rock the belly will damage severely.

At this point, this claim is just stupid in my opinion. I've posted photographic evidence of my own belly easily supporting 16% of the weight you say should crush me fatally. It's got a comparable pressure to your 18cm×18cm rock. I've told of supporting 40kg on my belly. I've told you where you can find videos of people supporting much higher weights, and malawi_glenn has posted videos of the same and has volunteered to place a 60kg weight on himself to demonstrate that he can survive it. And the only reason I'm not volunteering myself is that I don't have a 60kg weight to use.

 

[malawi_glenn]

I don't even know what is the issue here?
That water pressure is not "real" pressure?

I gave a good analogy with the sand, no respone

The peak pressure of this hit is more than 60kg on 18cm x 18 cm

The guy who was hit got a bruse, but no internal injuries and certaintly no death

 

[Yahya Sharif]

60 kg dumbell on my hairy belly tomorrow! Very small area too. Hope I survive

Thanks, I'm waiting.

 

[malawi_glenn]

Thanks, I'm waiting.

And I am waiting for your response regarding the hip thruster

 

[jbriggs444]

In contrary, a rock of 60 kg put on the belly* will crush the belly immediately.

First of all, no, it will not. That is an imaginary experimental result for which a real experiment is available.

Second, it is a slightly unfair comparison. On a supine human there is some stress already on the belly simply from laying supine. The belly must support itself in addition to any applied load.

 

[Yahya Sharif]

Here is a guy performing hip thrusters with 100kg barbell. The contact area is about 200 cm² which results in pressure ~ 50 kPa

perhaps those are actually green plates (10kg) which he painted blue and wrote "20kg" on? And use a "womens" barbell (15kg). That would make the total weight equate to 55kg. Or, this is also the case of some serious hollywooding.

The thighs are not sensitive as a belly. I made a video (post #109) of me lying on the concrete block with my weight of 59 kg and I bare it for 1 minute without stomach damage, the equivalent is putting a rock of 59 kg on the belly.

 

[malawi_glenn]

The thighs are not sensitive as a belly

He has the bar on the belly.
BTW the dude in the video, Daniel, is kinda hardcore at the gym, have met him a few times at some conventions. No idea why he is using the sissy-pad for this. Its just 100 kg.
Some people perform the excerise with the bar placed on the hip-bone, then you might need the sissy-pad. But not Daniel, he is the real deal!

I bare it for 1 minute without stomach damage

your flesh is weak.Perhaps I can shoot a photo tonight of me lying on my stomach on a small stool. My body weight is +100kg

 

[Yahya Sharif]

He has the bar on the belly.

In fact he has the bar in the place just between the belly and the thighs. This movement will cause the bar to roll on this place. This place is much stronger than the belly it has bones.

Perhaps I can shoot a photo tonight of me lying on my stomach on a small stool. My body weight is +100kg

The stool must be small in area that does not touch the chest the chest is strong and can bare your weight. So the measurement will not be accurate.

 

[malawi_glenn]

This place is much stronger than the belly it has bones.

Point is, for the majority of the movement, the bar is placed above an area of the body that is not supported by bones. I do that excerise myself regularly.

The stool must be small in area that does not touch the chest the chest is strong and can bare your weight.

Here is pic of me lying on a stool with about 20 cm x 20 cm area of contact.
Had no contact with any bone in my body.

This is the most pointless picture I have ever taken. My wife thought I was more crazy than usual.
I told her "Now I am going to die according to some kid on the internet and internet is always right"

I dedicate this one to @Ibix and @Orodruin

 

[malawi_glenn]

I did not die, but I just had dinner so it was not very pleasant to lie there for 1 min.
You have to eat protein rich food to get big and strong. My dinner was 0.5 kg quark and 0.3 kg swedish blueberries, some rice cakes with own made hummus. Do not neglect the veggies and healty fats (whatever that means). Avocado oil is my new favorite. I have about one tablespoon two times per day. Aim for about 1.5 grams protein / kg body weight. Drink plenty of water.

I guess thread can be closed since it is now proven that belly is not destroyed.
Paper will appear on arXiv on tueseday!