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/sci/ - Science & Math

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6191364 No.6191364 [Reply] [Original]

So on which side does it tip /sci/ having an argument with a couple of friends. Some are calling it will tip right, some calling it will balance out. I´m thinking it will tip to the left because of the weight of the pinball and string.

Can someone explain ?

>> No.6191367

imo it will balance, cause neither the force applied by the surface tension on the right nor the weight of the ping pong ball are significant enough to tip the scale either side

>> No.6191370

>>6191367

however if you account the weight of the ping pong ball and it's string it would actually tip left even if even by a REALLY small margin ?

>> No.6191385

bump for answer

>> No.6191393

I think the steel ball doesn't affect anything at all so it may as well be removed. The ping pong ball should be pushed up because it is less dense than the water below it, so I think the left will be pushed up.

>> No.6191404

>>6191370
yep.

>> No.6191417

>>6191364
it will tip to the right, someone please post the pic with all the forces drawn in before we get 200 posts of retarded answers saying it will balance/ go left.

the ping pong ball can be completely left put, it does nothing, the steel ball has a boyency force that will tip the right side down.

>> No.6191430
File: 1 KB, 125x51, this.jpg [View same] [iqdb] [saucenao] [google]
6191430

>>6191417

hydrostatic basic law ϱ*g*h*A= F at bottom, which is the same. add the forces on the LHS and youll see the resulting Force will pull upwards

>> No.6191440

>>6191430
ebin

>> No.6191441

>>6191393
are you really this retarded?

>> No.6191445

>>6191417
thats not how buoyency works

>> No.6191450
File: 23 KB, 800x600, draw.png [View same] [iqdb] [saucenao] [google]
6191450

>>6191430
Give us an interpretable picture you faggot

>> No.6191453

>>6191430
are you fucking kidding me with that picture

>> No.6191451

>>6191430
Could you make that smaller, please?

>> No.6191454
File: 66 KB, 1823x758, itrolu.png [View same] [iqdb] [saucenao] [google]
6191454

>>6191453
>>6191451
>>6191450
>>6191440

im sorry guys

>> No.6191471

>>6191454
Thanks for resizing it.

>> No.6191474

The tension in the string of the steel ball cancels out the extra weight it puts in the water, and the buoyant force of the ping ping ball cancels out the weight and tension forces that it adds to the water on the left.
It will balance.

>> No.6191483

>>6191454
Doesn't the steel ball have little buoyancy as it should sink to the bottom because its denser?

>> No.6191478

>>6191474
I weep for your generation.

>> No.6191495

>>6191478
Am I wrong?

>> No.6191501

>>6191483 buoyancy if i remember correctly, is related to surface area. Not density.

>> No.6191503

>>6191501
You are correct.

>> No.6191515
File: 334 KB, 647x597, Five.png [View same] [iqdb] [saucenao] [google]
6191515

>>6191483
Think of it as if the water in the right cup was pushing the inmovable steel ball from below, because all the water above have weight.

>> No.6191518

so the steel ball is supplying NO weight to the beaker on the right. But the ping pong ball is. Rest all is same. Tip to the left.

>> No.6191545

Need more information

>> No.6191567

I don't have the image, but I saw a proof using virtual work that showed the scale will, indeed, tilt right. I might work it out myself later if no one posts the image, but basically the fact the the metal ball is not connected to the scale means more water can go lower, minimizing gravitational potential energy, if the scale tips right.

>> No.6191570

>>6191417
>>6191567
2 correct out of 25 posts.
sci is smart tonight!

>> No.6191580

>>6191567
Doesn't this contradict what
>>6191515
>>6191417
>>6191454
have said?

>> No.6191606

>>6191580
did you even read one of those posts? some said right, other say left.

>> No.6191608

>>6191417
>the ping pong ball can be completely left put, it does nothing
Just because when submerged in water it wants to up doesn't mean it has no weight.

>> No.6191632
File: 41 KB, 396x528, water.jpg [View same] [iqdb] [saucenao] [google]
6191632

>>6191417
>>6191567
>>6191570
So you are saying that if I submerge a steel ball suspended on a cord into a jar of water placed on a scale, the weight of the water as indicated by the scale will increase, due to buoyancy (or virtual work or what have you)? I find that very hard to believe.

pic related

>> No.6191652

>>6191632
now I think that is indeed the case
fuck me right

>> No.6191656

>>6191632
It is sort of strange to think about, but yes. Buoyency is a great way to think about it actually. That force has to balance somewhere.

>> No.6191663

>>6191656
Yes I get it now.

>> No.6191664

>>6191656
So what would the difference be between this and if the cup were full of air and you suspended a metal ball from a string inside the cup?

>> No.6191673

>>6191664
Water isn't compressible (or, only a little bit compressible).

>> No.6191688

>>6191664

>>6191673 that's not quite it. If the cups were full of air, then the scale and cups and balls and everything would be immersed in the same body of fluid.

>> No.6191699

>>6191364
A person that I know did this experiment weighting the same container first with the ping pong ball attached to the bottom, and then with the steel ball suspended by a string. In both cases they were completely submerged. With the steel ball it weighted more.
If you want to know why, study the Archimedes' Principle and try to understand what happens. My English is not good, so I won't try to give an explanation myself.

>> No.6191698

tilt the whole thing counterclockwise by a very small amount dz. In the left the change of potential energy would only involve the weight of the water and the ball. On the right, only the mass of water and the force that the ball (which wouldnt move) exerts on the water (buoyancy with sign changed), would matter. These two contributions are not the same so the system isnt at equilibrium

>> No.6191707

>>6191699
A person that I know did this experiment weighting the same container first with the lead ball suspended by a string, and then with the steel ball suspended by a string. In both cases they were completely submerged. With the lead ball it weighted more.
If you want to know why, study the Archimedes' Principle and try to understand what happens. My English is not good, so I won't try to give an explanation myself.

>> No.6191709

>>6191364
The right side will move up.
Draw the forces to understand why. The steel ball supports some of the water in the right cup, be it as minuscule as it might be.

>> No.6191715

>>6191707
I'm not trying to create a copypasta you fucking idiot, I was serious.

>> No.6191748

>>6191715
A person that I know did this experiment weighting the same container first with the lead ball suspended by a string, and then with the steel ball suspended by a string. In both cases they were completely submerged. With the lead ball it weighted more.
If you want to know why, study the Archimedes' Principle and try to understand what happens. My English is not good, so I won't try to give an explanation myself.

>> No.6191755

Science was done

https://www.youtube.com/watch?v=b_8LFhakQAk

>> No.6191773

i actually just tried it, a gold ring (suspended by string) that weigh 13.5g increased its weight by 1.3g. So the metal ball would make it a little heavier, but still would not add 100% the weigh of the ball

>> No.6191783

The left side is a red herring, you could as well cut the string and let it float. The right side is connected to the 'outside' because the buoyancy reduces the tension in the string. This force has to come from somewhere and that somewhere can only be the right side of the balance. Conclusion: right side goes down.

>> No.6191790

>>6191783
your conclusion is correct, the way you go there was retarded and wrong.

>> No.6191801

>>6191783
>The left side is a red herring, you could as well cut the string and let it float.
But then the levels of water would not be equal.

>> No.6191831

>>6191801

but the mass would not change

>> No.6191833

>was retarded

feeling better now?

>> No.6191861

It's just the buoyant force of the steel ball vs the g force of the pingpong ball. Whichever is greater, it will tilt to that side

>> No.6191888
File: 48 KB, 701x494, pingpong.png [View same] [iqdb] [saucenao] [google]
6191888

>>6191364

>> No.6192015

>>6191755

>still arguing after this was posted

Holy crap guys, debate over

>> No.6193500
File: 222 KB, 2298x4759, 1384190257708.png [View same] [iqdb] [saucenao] [google]
6193500

>> No.6193505

>>6193500
>>6193500
only correct answer.

the buoyancy of the steel ball pushes down on the right side. only the mass of the ping pong ball pushes on the left side.

Right side heavier.

>> No.6193547

>>6191364
IF the vessels are equal
IF the fluids are equal
IF the diameter of the spheres are equal
the only difference between left side and right is the weight of the ping pong ball and the string holding it in place

therefore

the scale will tip left

>> No.6193552

>>6193547
>le epic troll
>guaranteed replies
>XDDDD

>> No.6193556

>>6191454
wrong

you forgot that the weight of the ball on the left is placed on the scale and the weight of the ball on the right is suspended by the stand.

>> No.6193563

>>6191501
buoyancy is dependent on volume (displacement)

something floats if it's volume weights less than a similar volume of the fluid it is placed in

>> No.6193566

>>6191888
yup

>> No.6193581

The right side will go down, because the bouyant force of the water on the heavy ball, pushes up against that ball. The magnitude of this force is greater than the added weight of the ping pong ball, since water is denser than the ping pong ball.

>> No.6193597

>>6191441
enlighten me then, genius

>> No.6193600

>>6191632
It will. Try it. If you lower a steel ball on a cord into water, the force on the cord gets less, as the ball gets lighter. That force doesn't just disappear into nothing. It is added to the weight below.

>> No.6193608

>>6191664
This wouldn't work, because there's air under the scale too, pushing up. However, if you put a heavier-than-air gas into the cup, it would work.

>> No.6193619

>>6193505
Actually, since the buoyancy of both balls push down on both containers equally, as shown in the diagram, the more correct reason to say why the left side goes up is that the string pulls it up. That is the unbalancing force. (Though people will no doubt give you shit if you say it.)

Saying the buoyancy force pushes the right side down is true too, since most people probably start by assuming the the left side buoancy is cancelled out by the string force, which is why they are going to give you shit. But I think the other way is a better way to think about it.

>> No.6193630

>>6191483
Buoyancy is a force due to the volume of a submerged object. If the object is heavier than the buoyant force, (like steel is) it will sink. If lighter it will float. But either way the force is there. In this case, the weight of the object is supported by a cable, so the weight is beside the point.

>> No.6193646

>>6193619
I'm having a hard time thinking about what would happen if the string was cut. I'm thinking that the result wouldn't change.

>> No.6193690

It will tip right. This has been posted several times and the answer is readily available on Google. Basic fluid statics is pretty much all you need.

>> No.6194003

There's the same amount of water in both glasses, so it contributes the same on both sides of the scale. We can therefore remove it without changing the balance. Doing this, you see that the right jar is empty, and the left jar contains a ping pong ball. The scale therefore tips to the left.

>> No.6194035

>>6193619
> the more correct reason to say why the left side goes up is that the string pulls it up
>the string pulls it up

Jesus christ, even high school retards know why this is wrong.

>> No.6194070

Protip: Newton's third law
The mass of the ball on the left determines if the scale is in equilibrium, more to the left, or more to the right.