How smart is Veeky Forums?

Do what this user said, and go back to 9th grade physics my dude.

Weight is not the same as mass. Mass never changes but weight depends on gravity acting on an object. You weigh less on the moon but you have the same mass.

0.5kg with miniscule fluctuations in response to the downward air pressure created by the flapping of the wings and the body of the flies, which add pressure inside the volume of air in the jar., which is so tiny it is not worth measuring.

ru dum bro, the scale knows that and corrects for it

about the wings flapping thing, the energy from the flapping is mostly lost to turbulence/is too weak to have and appreciable effect
now why doesn't compressing air in a tank make it heavier??? am I stupid?!

d-do wut pohsterr sad nd go bak 2 skoll ma dood

That's why it will only read 1 kg. For evert effect theer is an equal and oppositte effect

Go back to newtons laws brainlet.

>the person at the base of the pool does not feel an added weight onto it
They would feel the extra pressure from the rise in water level when the other person got into the pool. Depending on how large the surface area of the pool is it could be extremely small though.

Just assume they used the scale to weigh the flies before they were flying.

>doesn't compressing air in a tank make it heavier
It does.

1.5 kilograms. Even if the flies are in the air, they are still pushing air downwards with the same force as their body weight, to keep them in the air.

How do you expect to get any kind of accurate measurement with the contents constantly moving around? The ONLY answer is it can't be measured.

1 kg is the answer, I believe

The flies would only contribute to the weight force vector pushing on the scale plate if they have landed on the sides and therefore there is a normal/weight force action-reaction pair between the jar and the flies from the flies' weights.

Also .5 kg is a fuckload of flies for a 1 kg jar unless the walls are thin.

>t. libertarian

Equivalent queston: imagine that the jar weighs 1kg and there is 10^10000 kg of flies flying inside of it. What does the scale read? Can you imagine lifting the jar easily?

>0.5 kg of flies
>An average fly weighs 5 milligram
Therefore there are about 100000 flies in that tiny jar. How are they supposed to flap their wings like that?

kek

shit like this is why i never want to be a mechanical engineer

newtonian physics beyond freefall equations is magic as far as i'm concerned

It has to be 1kg if the flies are floating. Imagine scaling something outside and suddenly Ryanair plane overweight and broke your scale because it's flying above you

What keeps the flies in the air?

If the jar is a vacuum, 1.5kg.

If the jar isn't a vacuum, slightly greater than 1.5kg because of the weight of the air.

how would the flies generate lift in a vaccuum wtf

But it isn't above the jar it is contained within the closed jar. It doesn't matter that there is air all around the jar, in a vacuum the result should be the exact same 1.5kg

They wouldn't, so it'd be 1.5kg exactly in a vaccuum..

wrong

OK so what is keeping the flies in the air?

You're fucking retarded or a troll. Either or, you make Veeky Forums complete shit.

What is keeping the flies in the air?

This might sound stupid, and I'm not a regular here, but why would these flies have weight if they're flying? They may have mass, but in flight they don't have weight.

I think the flies have weight buddy.

>They may have mass, but in flight they don't have weight.

The flies need to exert a force equal to their body weight to keep themselves suspended, using their wings. The wings will use air pressure.

Alternatively if it is in a vacuum as stated, we must assume that this is an instantaneous representation of the flies, and while in a second they will fall, for the moment the scale would only read 1 kg, ie the weight of the jar. In a certain amount of time the flies will hit the ground, and once all of them have landed, the scale should read 3.5 kg.

It's an unintuitive question since flies don't weigh .5 kg so it's difficult to think of flies flying as exerting enough air pressure to make a difference on a scale. But if they weighed .5 kg they might. IRL, the weight is negligible relative to the weights scales are typically designed for

The weight on the scale will fluctuate within an average range between the sum of the weight of all the flies and the jar. Because they're creating air preassure when they flap their wings.

>Guys it doesn't weigh anything because there is air under it.

It is clear that half of Veeky Forums is fucking morons lets try this one.
Scale tilts to which side?

pong pong ball side?

Sigh...

If you put a scale under that hovercraft while it was in operation, it would not read the same as when it was turned off.

ping pong side rises obviously

The jar lifts me easily as the flies take off and carry me away to my secret evil lair

i am the FLYINATOR
MWAHAHAA

Steel ball side. The ball effects the total volume in the beaker?

Uhh nothing

You win.

Yeah but both balls do that. This is a question about force balancing and buoyancy.

It would read the weight of the hovercraft plus whatever the difference in weight between the pressurized air under the skirt and the air outside.

And the negative resultant differnce would result in a lighter weight than it turned off

if both balls have the same volumen, then the scale is in equilibrium

Can't tell if you are a moron or quibbling about the distinction between difference and absolute difference.

Try again.

density of fluid, volume displaced is the same for both. tension in ping pong ball rope = buoyancy - weight of ball, which pulls up on the scale. steel ball is not connected to scale. ping pong ball moves up.

Jesus fuck guys.
A buoyant force equivalent to their volume of water displaced is exerted on both balls. The ping pong ball is attached to the beaker so it's irrelevant, while the steel ball is attached to a string going outside the beaker. So an equal an opposite force is exerted downward on the beaker.
Fairly sure if you were to replace to ping pong beaker with a beaker filled with water reaching the save level, THEN they should be balanced.

>which pulls up on the scale
If I cut the string on the ping-pong ball the answer would be the same

you seem mad bro, dont get mad bro

>Fairly sure if you were to replace to ping pong beaker with a beaker filled with water reaching the save level, THEN they should be balanced.
Yeah water is assumed in-compressible so it doesn't matter at what depth the displacement is located.

You're increasing the density of the air but you're not introducing any new quantity of mass.

What the fuck is this even supposed to imply?

An empty and a full propane tank are different weights. If you don't notice a tank filling with air it's just because the pressure isn't high enough.

its obviously 1.5

Somehow there are quite a few idiots who don't see it that way.

its 1.5 kg its a 1kg jar full of .5kg (1+0.5=1.5)
don't be mislead by the picture they are dead i.e. not flying

>Sigh...
t. brainlet who can't explain because he dosen't know

The reason why it tilts to the right is because the buoyancy force on the steel ball is greater than the weight of the ping-pong ball and the string.

None of those 3 is correct.

its 1kg

No, it isn't.

Can someone qualified answer this question rather than having a bunch of Veeky Forumsentists argue over it?

>Can someone qualified answer this question rather than having a bunch of Veeky Forumsentists argue over it?
How would you know if any of us are qualified?

Well, I have a BSc in Physics, and I can tell you now that it is 1kg. Take it or leave it.

I don't. All I can do is believe that this user would be honest. That's all you can really do on the internet for the most part.

Why does OP keep saying it's 1.5?

the flies are in a vacuum you fucking retards
scale reads zero

Because it is.

What about the jar?

the jar is also in a vacuum you dunce

so it weighs 0?

>being this fucking dense

So there are many honest anons but some of them are morons.

It's a vacuum, it isn't dense at all.

Assuming equal amounts of water in the beakers and equal displacement by the balls, the ping pong side has the weight of the ball and the string on its side, not to mention the air inside the ping pong ball so the scale tilts to the ping pong ball side. There is a different amount of string submerged in each beaker though, so if the string isn't the same density as water that could affect the outcome.

bouyancy is proportionate to the volume of water displaced senpai
lol

And you literally can't pull yourself up by your own bootstraps kouhai.

what if you tied several helium balloons to the left side, then?

Air is less dense than water but exactly as dense as air. Why would the ping pong ball float in air?

because the string is taut, the buoyant force exceeds the ping pong ball's mass. because the string does not break, it is supplying a downwards tension equal to the difference of these two. since the string is in equilibrium, it also exerts an upwards tension on the left container.
that's how it works, right?

>that's how it works, right?
The tension on the string is equal to the added pressure on the bottom of the beaker from the increased water height minus the weight of the string and ping-pong ball. When you add up the forces the final result is just the net weight of the ping-pong ball and the string.

this

What about the buoyant force on the metal ball?

The flies are actually superflies that generate 2 mega Newtons of force to fly against gravity. The gusts created in the jar propels the jar upwards and the scale reads a max value of 200001 kg (2*10^5 kg).
If observed at normal human reaction times, the jar would have flown off and the scale would have read 0.

The weight of the water is the same on both sides: Mg, where M is the mass of the water. Neglect the weights of all strings.

On the right side, the water pushes up with a buoyant force B on the steel ball. This force partially cancels the ball's weight, so it decreases the tension in the string. The reaction force on the water increases the weight applied on the right scale by B, so the total weight on the right is B+Mg.

The left side has two forces acting on the scale other than the weight of the water: the tension in the string and the reaction of the buoyant force B of the ball. B is the same, since the balls have the same volume. If the ping pong ball has mass m, the tension in the left string must be B - mg because the ball is motionless. The force on the left scale is the difference between the reaction force on the water (B down) and the tension on the string (B - mg up) Thus, the force on the left is Mg + B - (B-mg) = Mg + mg. Since the ping pong ball floats, B>mg. Thus, the extra force on the right side (B) is heavier than the extra force on the left side (mg). The total weight is (B + Mg) on the right and (mg + Mg) on the left.

The scale thus tilts down on the right (steel ball) side.

You maintain them with an electro magnetic field

A perfect explanation.

Wouldn't it be like trying to lift oneself, which doesn't have any effect ?

I agree

You can do the fly thing in your kitchen. Put a bowl of water on a scale. Add something that floats in it. Look at the weight on the scale go up.
Replace water with air and it's the same result.

Between 1 and 1.5 kg because the forces exerted by the flies flying is still counted but by the time the air flow of their wings hit the bottom of the jar and excerce a force on it the force would have been reducted by the resistance of the air and the jar