Questions tagged [buoyancy]

Use "buoyancy" for any question where an object is suspended or submerged in a fluid. Buoyant force is the force that acts upward on a partially or completely submerged object.

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Trouble with two fluid buoyancy problem [on hold]

So I've given this problem a few shots and I cannot seem to get a reasonable result. Nor have I found anything really useful online. Here is the problem: A cube with length 10 cm and made of ...
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Is there more or less atmospheric pressure pressing down onto water having a larger atmosphere than of a smaller atmosphere?

Is there more or less atmospheric pressure pressing down onto water having a larger atmosphere than of a smaller atmosphere?
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32 views

Would a rigid object thats slightly negative buoyant sink all the way to the bottom of a 10,000 ft fresh water lake?

Would a rigid object thats slightly negative buoyant sink all the way to the bottom of a 10,000 ft fresh water lake? I'm going to make a few questions regarding the topic involving a submarine & ...
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A basic question of positive buoyancy,

Positive buoyancy occurs when an object is lighter than the fluid it displaces. The object will float because the buoyant force is greater than the object's weight. But I also read, buoyancy ...
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2answers
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How do I calculate how much weight is needed to sink a specific amount of air and for how deep will it sink? Understanding buoyancy

I'm trying to understand buoyancy so I created a question that should help me greatly. To keep this simple my above is a photo is of a 20 ft long tank. Each line represents 1 cubic ft which each holds ...
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79 views

Hydrostatics and Buoyant Force

In the below problem the weight of the rod acts at it's centre (the centre of mass). But how do I know from the buoyant force acts? How do I proceed with the rest of the problem? Here's my attempt to ...
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Would the buoyant force increase if I inflated a balloon that's inside a closed chamber hypothetically submerged underwater?

Would the buoyant force increase if I inflated a balloon that's inside a closed chamber hypothetically submerged underwater? And vise versa would the chamber's buoyancy decrease if deflated? I ...
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3answers
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Why the submarine sinks into the bottom of ocean once it starts to sink?

An inflated ballon will rise yo a definite height once it starts rise where as a submarine will always sink to bootom of ocean once it starts to sink, if no changes are made. How then can a submarine ...
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Wouldn't buoyant force be the same for the two bodies?

A foam is attatched to a concrete (both having different volume) by two inextensible wires. The entire system is submerged in water (in equilibrium), though not sunken, with the water just touching ...
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2answers
39 views

Vacuum balloon / airship with balloons as shell segments

What are the problems with the following idea for building a vacuum balloon / airship? The question is targeted at the "making it float" part, ignoring other problems with super-light airships (...
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I can't prove the Archimedes' principle in a particular case [duplicate]

If I put the cylinder on the bottom i replace F2 with normal force N. But it will be at most equal to F1 plus the cylinder weigh N=F1+$\rho$gV. So how can it get a bigger boost from the bottom to be ...
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Ice Melting with a Twist [closed]

The Question There are three ice cubes floating in three different cups of water. In the first cup, the ice cube has a pocket of air inside. In the second cup, the ice cube has a pocket ...
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A simple though experiment: molecular sieve + buoyancy = perpetual motion?

The picture below is a low-effort mock-up I made showing a closed loop with uniform ambient room temperature and top-down gravity containing two species of gas—although the idea may apply equally to ...
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Would “buoyancy” / lift power increase if you compressed helium or hydrogen towards 1/infinity?

Of course, my inclination says that density should increase then, having an opposite effect but at the same time, i am inclined to believe that by fitting more helium in a "ballon" would allow more ...
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Would I have to add any additional weight at the end of the lever of well pump (B) for it to lift the same amount of water as did well pump (A)?

The question is if I would have to add any additional weight at the end of the lever of well pump (B) for it to lift the same amount of water as did well pump (A)? My assumption is yes because of ...
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Buoyancy of a balloon filled with heated water vapor [closed]

Why not fill the balloons not with heated air, but with heated water vapor, for example, placing a container of water between the burner and the neck of the ball? Obvious advantage: water vapor is ...
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21 views

Buoyant force on partially submerged object

Is the force exerted by the liquid, in which the object is floating, same as the buoyant force exerted by the liquid? I am confused since the object is assumed to float with some part of it above the ...
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1answer
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In swimming why does gliding help keep the head out of water

In relaxed non-competitive swimming, it is possible to keep the head out of the water while gliding. This can be breaststroke or backstroke (or doing the Tarzan stroke in waterpolo). What is the ...
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Time taken by bubble to come to surface

Does air bubble take same time to emerge from shallow water and deep water? I think the acceleration due to buoyancy will be the cause.
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1answer
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Why is this balloon following me?

There is a mylar (shiny) helium birthday balloon tied to a chair about 2' (60 cm) away from me. It has some freedom to move around because it gradually lost helium & sank a little which reduced ...
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4answers
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What is buoyancy?

I’ve seen answers which cite newton’s third law as the cause for buoyant force, but wouldn’t this mean the moment an object of any weight is placed on a fluid, the fluid would immediately exert an ...
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Can density replace buoyancy?

Recently I discussed the possibility of a flat earth, with a flat earther whom rejected much of established science, especially newton and his laws because Newton's idea of gravity rendered a flat ...
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2answers
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Would a fluid in free-fall exert a buoyant force on an object submerged in it

I’m not sure I 100% understand the buoyant force on the atomic scale. I know the force is due to pressure exerted on the object, due to the volume of the fluid that the object displaces. I’m under the ...
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Does the mass of a beaker filled with water change due to a mass partially submerged in it?

I believe it should be different as there is upthrust acting on the second block and hence by Newton Third's Law it should act back on the liquid adding to more weight. The answer is given isn't so as ...
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Pressure and upthrust force

What is upthrust force? Is is the pressure difference or just pressure x Area at the bottom of the surface? How does upthrust force change with depth in liquid?
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The physics of the startup of a lava lamp

I noticed a strange phenomenon observing a lava lamp. We all know the complex flow of bubbles when the lamp is "hot" and running, but I would like to have some explanation about the startup behavior ...
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Why does a helium balloon rise? [duplicate]

This may be silly question, but why does a helium ballon rise? I know it rises because helium is less dense than air. But what about the material of the ballon. It is made up of rubber/latex which is ...
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3answers
84 views

Does the weight of a steel ball changes when submerged in water? [duplicate]

Will there be a difference in the weight of just the ball under water Vs in normal atmospheric pressure conditions i.e. a weighing scale with the steel ball on it Vs in vacuum assuming earth's gravity ...
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4answers
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Does a non-buoyant (denser than water) object (such as a lead diving weight) weigh any less when submerged in water?

I've just been discussing this question with my eldest son, who is an extremely intelligent man, as well as being an engineer, a sailor and a scuba-diver, and he believes that an object heavier than ...
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4answers
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Would a helium ballon pop or freeze in space?

I have read these questions: Why doesn't Helium freeze at 0K? Do objects in space freeze immediately? Now I do understand that a helium balloon cannot float up to space. But let's assume this ...
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3answers
81 views

Will buoyancy act on B? [duplicate]

A is immersed in water, buoyancy must act on A; B is at the bottom of the container, there is no water between B and the container, that is to say, the bottom of B is not in contact with water, so ...
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3answers
191 views

How to make a object stay under water?

How to make an object submerged under water? Neutrally buoyant? Thank you
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5answers
284 views

Does Archimedes principle account for depth?

The principle states that the upthrust acting on an object is equal to the weight of the fluid displaced by the object. However, this to me suggests that no matter how deep an object is immersed in ...
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7answers
212 views

Is there any opposition to gravity? [closed]

we have friction which opposes motion of moving body on another surface, resistance or reactance which opposes current, reluctance which opposes flux etc ,each and every physical phenomena there is ...
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2answers
64 views

How do floating wind turbines stay upright?

Some designs for floating offshore wind turbines have asymmetric bases. Why, however, is the turbine sometimes based on the downwind side of the float as seen here and here? And, related, what ...
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How can I get the height that sits above the waterline of a partly-submerged object?

If I know the density of water (say 1024 kg/m^3) and the density of ice (say 900 kg/m^3), and the volume of an object (say 8 x 10^9 m^3), how can I figure out how much of it is sitting above or below ...
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Buoyancy question

Suppose we have a ball of volume V and a block of the same volume V whith same density. We submerge the ball into some kind of liquid so that $\frac{1}{2}V$ is submerged into the liquid. We do the ...
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1answer
189 views

Buoyant force when object is between two liquids

Suppose we have a ball floating in liquid A. Then we pour a liquid B on top of the ball (Assuming that the liquid is poured such that the ball doesn't oscillate) . The ball rises up. Why? According ...
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3answers
56 views

What is the physical origin of buoyancy?

Imagine a horizontal cross-section $\Delta S$ of a cylinder containing a liquid of density $\rho$. The downward pressure on $\Delta S$ at the depth $d$ from the surface of the liquid is $P_{down}=\rho ...
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1answer
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Is there any weight diffenence between sealed/unsealed bottles? [closed]

I have to prepare my chemical report about CO2 molecular mass. I searched and got a sample report from internet. I read it and I can't understand this. Weight of flask covered with glass cover = ...
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1answer
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Energy balance of this machine is positive. What is wrong? [duplicate]

Machine on this picture is inspired by video: https://www.youtube.com/watch?v=rxFXsoqbfrk There must be error in the computation of energy balance or there is another negative energy. Can you help ...
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0answers
41 views

How do the principles of weather vane design change for underwater applications?

I am doing some research into the use of weather vanes under water. This "water vane" would serve the same function as a weather vane does in air, just while submerged in water. I understand that ...
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2answers
125 views

Bouyant Force Confusion [closed]

I was asked to solve the question in the picture I naturally thought the answer was (1) because bouyant force is caused by the pressure difference on the object's top and bottom surfaces. Turns out ...
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1answer
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Bouyancy of ozone gas

If ozone is $O_3$ why is it an outer layer of the atmosphere? It seems $O_3$ would sink in a solution of $O_2$, rather than float on it.
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What are the horizontal forces on a heeling ship?

Consider the following image from Wikipedia: The article states: "Whenever a floating body in a liquid is given a small angular displacement, it will start oscillating about some point, called the ...
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1answer
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How can I get an idea of what is the volume of the air displaced by an object totally immersed in it?

My specific problem is that I can't figure out what object displaces more air, a rigid closed container or a similar container that is opened. For example, let's think in two similar bottles with ...
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1answer
115 views

How to calculate the normal force of a box in the bottom of a bucket of liquid? [closed]

I have been trying for some time now, and seem to be unable to come up with the correct answer. The setup for the problem is as follows: After finding a similar question and rechecking the buoyancy ...
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1answer
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How can one the find normal force of a block resting on a pool floor underwater?

There is the force of gravity on the block, the atmosphere, the water pressure o top of the block, but how about between the block and the floor? Would we calculate water pressure pushing up from the ...
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1answer
33 views

How do fluids behave in space with regards to bouyancy and density?

Will a fluid loose it's bouyancy in zero-gravity. What would happen if an object is immersed in a liquid in space (if the liquid is still very much together and not spilling as big bubbles or droplets)...
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1answer
62 views

Floating object and buoyancy force

A cubical object of side 100cm floats over a fluid of specific gravity 1.6. The depth of immersion is 75 cm. The centre of buoyancy lies 25 cm below the surface of the fluid. When measured from the ...