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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water surface tension and buoyancy

When you put a little pin on the surface of water and it floats. Is this because of surface tension or buoyancy? Can somebody also draw a force diagram for me to explain how water surface tension ...
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Archimedes' principle: innacurate terminology? [duplicate]

All around I read that buoyancy is numerically equal to the weight of fluid displaced by a submerged object, the volume of displaced fluid being equal to that of the submerged portion (Wikipedia). ...
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368 views

Balloon, lighter than air and vacuum?

As I understand, in a balloon/air balloon, a gas burner is used to heat air or using some lighter atom like helium. Since helium or hot air is lighter and less dense than the cool air around the ...
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1answer
259 views

Upthrust vs Drag

24: A ball is falling at terminal speed in still air. The forces acting on it are upthrust, viscous drag and weight. What is the order of increasing magnitude of these 3 forces? ...
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1answer
88 views

I need to find a formula between the weight of an object and the volume of the buoy that can float it on water

So my problem is that i am working on an art instalation that needs to float. The idea is that i need to find a formula between the volume (V) of the buoy and the total weight of the whole ...
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6answers
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Why does ice melting not change the water level in a container?

I have read the explanation for this in several textbooks, but I am struggling to understand it via Archimedes' principle. If someone can clarify with a diagram or something so I can understand or a ...
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2answers
142 views

Can a solid object float on a frictionless liquid?

Assuming the solid is less dense than the liquid, will a solid object float on a frictionless liquid? I can imagine that due to the pressure gradient the object will float, but I can also imagine ...
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100 views

Anchor of a boat

hope you can help I've been teaching my kids about pirates and when we were talking about pirate ships this morning I confused myself greatly. When carrying an anchor a pirate ship (or any vessel ...
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3answers
437 views

Does gravity cause Archimedes' principle and how?

Why do lighter objects float and denser sink? I understand this from the perspective that if the object can displace the equal mass of water it will float, but I wonder from the perspective of ...
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2answers
170 views

If the MH370 black box did sink to 15000 ft, how long would it have taken?

I have been following MH370 on the news just as everyone and latest reports seem to indicate that the black-box could be found. A recent info-graphic http://t.co/lyBBE9C2hF shows the insurmountable ...
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3answers
224 views

Question about buoyancy

I took an empty clear sphere with radius r, put some weight inside this sphere, and put in into the water. I calculate the buoyancy force as: Volume of the sphere = Volume of the water displaced ...
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1answer
126 views

Different solutions for floating a DIY torii gate deeper than it's original floating level [closed]

I'm facing a dead end with my physics experience on a new build I am working on. Any help would be appreciated. Basic problem: I am trying to build a floating wooden Torii gate to be placed on water ...
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2answers
501 views

Beryllium Vacuum Sphere Boat/Aircraft

Is it possible to make a solid rigid evacuated "balloon" out of Beryllium or other elements or alloys? The critical buckling pressure at which an evacuated sphere is given as $$ ...
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29 views

Sensor Temperature with time constant [closed]

I am having trouble with this question on my study guide. I can't seem to find anything on my previous lectures to help me out with it. It is part of my study guide and I think it will be on my exam. ...
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2answers
76 views

Stratospheric ship

Let's assume that we build a giant steel hull in a shape of cube with open top (2km long edge) and lift it to the top of stratosphere and then pump air out of it. Would it float on the outer layer of ...
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1answer
401 views

Effect of waters changing specific gravity on objects apparent weight placed in liquid

My goal is to monitor the change in specific gravity of a liquid over a period of time. My question is: What are the appropriate formula for determining expected apparent weight of an object immersed ...
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2answers
274 views

What is the third law action pair of buoyancy?

Consider a block floating in a fluid. The force due to gravity balances the buoyant force exerted on the block. But there must be a third-law action pair to the buoyant force. If the block exerts a ...
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2answers
67 views

Buoyancy of a positively charged object inside positively charged fluid

An object with a density of $x$ inside a liquid with a density greater than $x$ would float. If we assume that both of these are positively charged and the object is in the middle of the liquid: ...
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1answer
151 views

How to model a rising helium balloon?

I'm trying to model the ascent of a helium filled weather balloon from 0km to 25km altitude. The plan is to eventually use a python script to calculate the time taken to reach 25km. However, I don't ...
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1answer
70 views

Will a rotating body gain linear acceleration in water?

If a ball is floating in water and it has some angular velocity, will it gain some linear acceleration from the drag on it as it rotates? Edit: This is how I pictured it. I guess my reasoning is ...
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1answer
88 views

Can we make rigid floating helium spheres?

Is there any material that we can make rigid floating helium spheres out of without it collapsing? I have been playing with surface area and volume formulas and with a bit of trial and error have ...
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3answers
558 views

Archimedes' principle for two liquid layers

Problem: I have a cylindrical vessel of height $H$ and radius $R$. There are two liquid layers in the vessel. The first has density $D_1$ and height $h_1$, the second has density $D_2$ and height ...
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1answer
536 views

Newton's second law, gravity and buoyancy [closed]

A body of mass $m$ and volume $V$ is immersed into the sea. The body moves under the action of two forces: gravity and buoyancy (Archimedes). Gravity force has a magnitude $mg$, where $g$ is a ...
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8answers
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Why does a helium filled ballon move forward in a car when the car is accelerating?

I noticed that when I had a helium filled, latex ballon inside of my car, it moved forward in the cabin as I accelerated forward. The faster I accelerated forward, the faster the ballon went from the ...
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1answer
362 views

How to calculate upward force of a container filled with a less dense gas than the surroundings where it is placed?

I'm trying to determine the calculation which would state the upward force of a container where the density inside the container is less then that in which it sits. Does this calculation change with ...
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4answers
2k views

Can air bubbles sink at extreme depths? [duplicate]

I was thinking earlier about air bubbles in water. if you had a bubble of air (say in a balloon) then as you take it down in water the bubble shrinks because of the pressure and because it is ...
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1answer
735 views

What is the buoyant and viscous force acting on a ball in free fall?

I was thinking about a situation were I have a long cylindrical jar with some viscous liquid in it. I also have a spherical ball with me. I drop the ball into the liquid inside the jar with some ...
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Buoyancy of compressed air

In the movie Transporter 3 a submerged car is floated to the surface by filling a large bag with air from the tyres. I know that movies are about the worst places to get examples of physics in ...
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1answer
551 views

Plastic bottle floating and sinking

I was doing this experiment: i take a plastic cup, put in a container of water, it floats – then when I put a coin in the water, it sinks and rests at the bottom. So to make the cup sink, i fill it ...
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1answer
343 views

Can the buoyant force on an object be seen as reduction in weight on a scale?

Consider a container with some fluid of density $\rho_l$ and volume $V_l$. This is kept on a measuring device and has weight $\rho_l V_lg$. Now, consider a block of density $\rho_b$ and volume $V_b$. ...
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1answer
2k views

Definition of Buoyancy Flux

I've seen in some papers the definition of buoyancy flux as follows $$B = g \frac{\rho_a-\rho_0}{\rho_0}Q$$ where $g$ is the gravity acceleration, $\rho_a$ is the density of the ambient fluid, ...
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1answer
186 views

Buoyancy in muddy water

Consider the buoyancy force in water with very small but macroscopic particles in it. Such particles (suspension) will very slowly drift downwards and will eventually settle on the bottom. If one did ...
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1answer
139 views

Time to immerse in a fluid

Whenever you drop an object in water, it takes some time to get fully immersed. I was wondering if this depends upon the buoyant force of the water on the object, slowing it down. However, I was not ...
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1answer
107 views

Are the forces I'm using correct? (ball in air) [closed]

I have been working on a program which should simulate all the forces on a spherical object. Right now those are balls, but they can easily be changed to something else. These are the formulas I use ...
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279 views

Help with buoyant forces and liquids (high school physics)

I am stuck on this problem. Here is the scenario Suppose you send a balloon (filled with air) from your submersible craft to the surface of the ocean, $10.8 \text{ km}$ above, with the ...
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389 views

Buoyancy Problem - Cubes in water

I have a tank with water (10 m high) , with an ideal seal at the bottom (water can't fall down, but can enter bodies). I have a system of 6 cubes ( of polystyrene density= 20 Kg/m^3) with dimension ...
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2answers
234 views

What is the sensation by man carrying a water bucker with an object floating in it? [closed]

A man is carrying a bucket with water. If a object is kept in it which floats in water, man will feel 1) heavier 2) lighter 3) none I think when the body floats its weight is balanced by upthrust ...
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1answer
135 views

Lifting house with balloons [closed]

I have an assignment about the movie Up. Here is the question: Critique the brief floating scene. Did the animators use enough balloons during this scene? What important variables, (which affect ...
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1answer
3k views

Floating Objects and Weight

The Situation: A ball is placed in a beaker filled with water and floats. It is also attached to the bottom of the beaker via a string. The Question: The ball is attached to the beaker, thus ...
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1answer
128 views

Finding the work required to move an object under pressure without knowing volume

"What is the least amount work you must issue onto a silver ingot with a mass of 38 kg at 26 meters depth to bring it to the surface?" I'm not sure how to do this one. Surely it depends on the volume ...
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1answer
995 views

Application of Archimedes Principle

A candle is floating in a liquid placed in a container. The container is a cylinder of diameter $D$, and the candle is of width $d$. ($D>d$) The height of the liquid from the bottom of the ...
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how dense fluid affect the buoyancy force?

I read a story regarding the Archimedes' principle in a magazine of popular science and I am thinking of the following question: how does the density of the fluid change the buoyancy force for the ...
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1answer
480 views

How does the buoyant force on a cube at the bottom of a tank of water manifest itself?

Let's say a 10N cube (in air, on Earth) rests flat on a scale at the bottom of a tank of water, and the scale reads 8N, so there is 2N of buoyant force on the cube. How does the buoyant force ...
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1answer
123 views

Measure density with the help of buoyancy

I am trying to derive a formula to calculate the density of a irregulary shaped object. I can measure the (false) weight of the object in pure air (of known density), and the (false) weight of the ...
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4answers
381 views

Can a balloon be used as an anchor point for a pulley?

For a physics/ engineering contest, I want to use a large balloon as an anchor point for a pulley. This would allow me to raise and drop masses. However, in testing, when I pull on the pulley the ...
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1answer
295 views

When moving something by entrainment in a fluid stream, where does the energy come from?

The particular Something I had in mind here would be air bubbles that are pulled downwards against their buoyancy by a stream of water falling down a shaft. The work required to push those bubbles ...
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1answer
289 views

In a column of rising hot air, is the velocity higher at the top?

Since the movement of the air is induced by buoyancy, i. e. there's a constant force acting on the air, so I would expect the velocity to increase during ascent, much like an object falling down due ...
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730 views

How do I correctly express the work required to put an object with positive buoyancy down into a certain depth (of water)?

It seems to me that I can express the work required to put an object under water in the same way that I express lifting an object up against gravity. I. e., in both cases I increase the potential ...
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How do I calculate the energy balance of a trompe?

I was quite fascinated by the concept of an ancient type of air compressor, called a trompe. It entrains air bubbles into a falling stream of water via the Venturi effect, and extracts the air at a ...
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61 views

Displacement of a Rock Thrown Overboard [duplicate]

Possible Duplicate: Basic buoyancy question: Man in a boat with a stone If you have a large boulder on a boat, in a pond, and you throw the boulder overboard and into the pond, would the ...