I didn't pass highschool physics

35lbs. This is why it's important to have a spotter for bench so when you load the 45s you don't flip the bar. They need to go one at the same time .

>>42289194
1

you need to have your spotter put the other plate on simultaneously or else it will tip

>>42289205
fuck you beat me to it

>>42289194
You can safely load 1.5 plates on a 45lb Olympic barbell

>>42289194
depends on how many are on the other side senpai

You fuckin morons. If putting a 45 on one side is gonna flip the bar, then just put a 45 on the other side first to balance it out.

>>42289194
use a bench that has those little hooks you can flip up to hold the bar on the empty side

>>42289231

This is what I do. Seems obvious tbqhwys

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>>42289194

I know for a fact that I can put two plates on my bar before it tips

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>>42289231
Genius

>>42289231
Or just put both it in the middle first, then move them to the edge

>>42289269
whoa...

>>42289205

this is quality bait

>>42289269
The middle of the bar isn't built to have that many plates on it - you may end up snapping it in half

>>42289194
Sum moments about the pivot point

Moment = force × distance,

Force in this case will be mass (kg) × 9.81m/s^2

The bar's centre of gravity is in the middle, and lets say it weighs 20kg, and is arbitrary lenght D from the pivot point.

The weights then have mass M and are an average of distance d from the pivot point (this you'll have to get by averaging the mass of each weight and its distance from the pivot)

So:
Left=20x9.81xD
Right = M×9.81×d

If, right < left, it won't tip

2 45s and a 25 on one side with nothing on the other side will make it tip

>>42289288

Kinda, but that shit flipped over in high school because people couldn't unrack

>>42289297
wow you really tried to sound smart about saying nothing

>>42289335
I have a PhD in Physics you fucking idiot

I think the lever arm of the barbell exceeds the amount force that is at other end of the barbell. Also a lot of the weight is located at the pivot point.

>>42289335
No, i literally just explained how to work it out from first principles.

If you're so scientifically illiterate that you cant understand highschool physics, consider gassing yourself

>>42289349
Not the guy you replied to

>>42289362
Me

>>42289362
can confirm the math checks out

Did some napkin math which gave me a tipping point of 5.8pl8. But in the cage at my gym the bar tips at 2pl8, so one of my assumptions must be wrong. Anybody know how the weight is distributed in a standard barbell?

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>>42289297
>that guy who brings a notebook and a tape measure to the gym so he can calculate how much weight he can load on the bar before it tips

Most benches and racks won't tip with 2pl8 on one side, but I've never gone past that. I think the math above checks out but not sure how you would estimate the mass of the barbell on each side of the pivot point, given that a barbell is not a completely uniform object.

>>42289349
How is it being unemployed?

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>>42289231

Only barbell is 7' and 20kg

Well call the two actual weights of the barbell 10kg and say they're resting on the two slots and are 5' apart.

Let's say the weight is being placed at average 6" outside of the rack slot.

On one side we have 10kg 5' (60") from the pivot point.

On the other side we have x kg 6" from the pivot point.

So 10(60) = x(6)

x = 100 kg, about 100 kg should tip it

>>42289754
>mixing metric and imperial

>>42289754
2 pl8 does not tip it though, not on any rack or bench I've used.

>>42289629
I think we're best ignoring the mass lost to knurling and connection. I can't find any info on the diameter of the collar though; I'm guessing about 65-70mm?

Sleeve volume = 415 * pi * (50/2)^2 = 815e3 mm^3

Collar volume = 30 * pi * (70/2)^2 = 115e3 mm^3

Bar volume = 1310 * pi * (28/2)^2 = 807e3 mm^3

Total volume = bar + 2*(sleeve+collar) = 2667e3 mm^3

Density = mass / volume = ~7500kg/m3, which is in the right ballpark for iron or steel

I know having 3plate will make it flip over.
Not sure about the exact weight though

>>42289205
lol a guy IRL asked me to do this with him so the bar didn't flip, I bet he goes on /fit/

>>42289224
how do you insert the .5 plates ?

>>42290609
this is why I love trebuchet

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>>42289231

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On THE 20kg(45 LBS) barbells att My gym it is written max 45 kg on the Side.
Thats like 2.25 plates

>>42289312
In my experience its 2pl8s and a 35. Might be because of different racks though.

>>42289754
are you saying 100 kg on one side? so 4½ pl8 on one side before it tips?

>>42289870
2pl8 is 40kg you melon

>>42289587
Would it matter? The weight of the barbell is distributed in the centre because its symmetrical. The positioning of the plates is what matters.

>>42290850

It depends on the rack. A wider set rack will be more stable.

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>>42289231
This is the first post on /fit/ to make me audibly laugh in months

>>42289297
no units/10
pleas gibe back ur phd

The most I leave on one side at a time is 2 plate, and that's after pulling the empty side of the bar as far as it can go to my side.

>>42291820
That's what I said faggot. Fuck you

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>>42289231
>>42289205

I fucking love this board

>>42289297
this,
good stuff engineer bro

>>42289297
>xD
Summer...

>>42289194
Dumbass a bar is 45 pounds so if you load lmao1pl8 on 1 side it'll flip. That's why I always get a spot for bench and squat

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>>42289231

>>42291804
yes it matters because the pivot point is not at the centre of the barbell. what matters here is moment, which factors in the distance of the weight from the pivot point. If the barbell carries significantly more of its weight at the ends it will create a larger moment compared to a uniform rod

>>42289297
you can't use the bar's mass as 20kg and the centre of gravity as the middle since part of the barbell will be over on the other side of the pivot point. you have to add up the mass on the side of the pivot without weights (which will be less than 20) and find the centre of gravity on that (which won't be that simple since the barbell's mass is not uniform along its length)

finally, you also need to factor in the end of the barbell's weight along with the weight of the plates when calculating on that side.

>>42293358
forgot to mention, if you have two supports holding up the barbell on a rack, you'll have to add in the reaction force from the support when calculating for moment.

feels bad though that the only practical use of studying mechanics so far is to be autistic on the internets

>>42289349
I don't fucking care, I just want my coffee

>>42289194

2 In almost every setup. 3 in setups that are wider.

>>42292834
absolutely kek