# Tagged Questions

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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### Buoyancy from ultradeep air/helium cavity

I would like to get some insight into a component with a sealed chamber of air which is submerged in water and forced down to a depth x. As the air has no communication with the outside of the cavity, ...
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### Is the top of an iceberg floating above the waterlevel equal to the expanding of the whole iceberg?

When water freezes it expands and is getting less dense. But is this expansion of the total iceberg equal to the top of an iceberg floating just above sealevel?
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### Calculation of buoyancy in a stratified water tank

I'm trying to calculate the buoyancy force in a stratified water tank. The model of my tank looks like this: Now I'm expecting cell 5 with Temperature $T_5 = 50^\circ C$ to have an upward buoyancy ...
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### Buoyancy and natural convection in a stratified water tank

I'm working on a simple calculation-model for a hot-water-storage. At the moment I'm stuck on implementing natural convection. To calculate the temperature I've implemented a simple 1D-model in ...
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### A dead body floats with its head immersing in water . Why?

I found this question in my practice book . I want to know about it .
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### Which one would has a greater magnitude, the viscous drag or the weight of the bubble?

An air bubble in a tank of water is rising with constant velocity. The forces acting on the bubble are X, Y and Z as shown. What describes the three forces? A) Z is the viscous drag ...
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### Velocity of displaced object [closed]

If I were to submerge an object in a large body of water and it is buoyed upwards long enough for it to almost reach terminal velocity, what would be the object's maximum velocity once it reaches the ...
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### How can I determine whether balloons inside a balloon are filled with the same gas?

We recently awarded ourselves some helium balloons to celebrate something, and they came with about a dozen little balloons inside, filling it to just under half way. I was discussing with a ...
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### Why is the center of buoyancy located at the center of mass of the displaced fluid volume?

Consider Archimedes' principle Any object, wholly or partially immersed in a fluid, is buoyed up by a force equal to the weight of the fluid displaced by the object. I do not understand why the ...
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### What is the direction of buoyancy in the bulk of liquid on earth?

I have a trouble when considering the direction of buoyancy in the bulk of liquid subjected to vertical temperature gradient. The liquid is heated from below or above that induces a natural convection ...
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### Help with Buoyancy

An object floats in both water and oil. Oil is less dense than water. While floating, the object displaces a larger volume of oil than water. why is the buoyant force the same in each liquid ?
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### Does Buoyant Force always act upwards?

I have always used buoyant force as acting upwards in any problem related to fluid mechanics that I have solved. Also, if we push a mug down a bucket of water. It rises up, always, not diagonally even ...
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### does buoyancy depend on orientation?

Let's say we have a sheet of steel of 1m^2 that is relatively thin. Will the buoyancy be the same if the sheet is fully immersed and placed horizontally inside the fluid with the buoyancy if the sheet ...
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### Dependency of buoyancy on volume and mass of submerged object

When we fully submerge a volume of 1 litre, whether that mass is 1 kg or 100 kg, isn't the volume of the displaced liquid always the same and equal to the actual 1 litre, i.e. to the volume of the ...
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### does buoyancy depend on shape and volume?

IF buoyancy is due to the pressure differential as we go deeper in a liquid, then that pressure differential should depend on the vertical dimension of the immersed object. Eg. if we have a long ...
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### Will it sink under circumstances? [closed]

I'm a 10 year old with a question. If you have a waterproof box the shape of a prism with an open top and you have a lid that fits perfectly in the top and you fill the box with water then put the lid ...
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### Trouble with basic Buoyancy : a treasure chest on a raft

I'm having trouble sorting through the following problem: You are shipwrecked and floating in the middle of the ocean on a raft. Your cargo on the raft includes a treasure chest full of gold that ...
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### Where does an object with density lower than outer space go?

Assume there was an object with lower density than that of the interstellar medium (which is extremely low already at just a few particles per cubic meter). If that object were released on Earth, ...
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### When a body just floats on a liquid (density of body and liquid being equal) and a force is applied on the body, it oscillates. Why?

Can someone explain this in terms of apparent weight of the body or law of floatation and NOT in terms of an equation of oscillation?
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### No buoyancy inside liquid [closed]

The answer to this question is given as (a) 5m. Due to the difference in pressure at the curved parts there will be a net upward force of buoyancy. And how can that be calculated without knowing the ...
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### Helium Lift Potential [closed]

A particular mass of helium is required to lift a particular weight. If the weight stays the same and the mass of helium is decreased can the same lift force be achieved by increasing the ...
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### Need to understand concept of Buoyant force

I want to know that is there any influence created by shape of container when apparent weight is calculated for example in following figure apparent weight in all container will same or not.
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### Energy Conservation in Kinetic Power Plants [duplicate]

Quite recently the company Rosch has developed a new kind of power plant that supposedly utilizes the buoyancy effect to generate electricity. The apparatus consists of a vertical conveyor belt with ...
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### fluid properties-state of body in motion under the fluid surface [closed]

Body is moving downwards in the fluid with uniform velocity.So, buoyant force = weight of the body. What will the state of the body represent:- sinking or submerged? p.s:The doubt is regarding the ...
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### how buoyancy in gases exists?

When considering buoyancy in a gaseous medium, if the gas has the same density everywhere, is it possible for buoyancy to exist? Or the gas need to be more dense in the lower layers for the buoyancy ...
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### Hot air balloon trajectory predictions

Hey there Physics friends! I've been struggling with what seems to be a very basic physics question. Let's say that I have wind vector for a given altitude and location, and I want to calculate the ...
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### Difference between water and ethanol density for an object [closed]

I'm just slightly confused. Say that I had an object that floated 19.4m in water from the bottom of the object to the surface. Now I was going to change the fluid to ethanol, which has a density of ...
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### why does an object float in the centre of water?

It is pretty clear from archimedes that how an object behaves in terms of floating and sinking when submerged in a liquid is cleary a matter of density of both the object and the liquid. SO consider ...
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### When a rocket or car is accelerating is the air in it going backwards or not?

I'm not sure but when a car is accelerating is the air in the car pushed backwards or not? If so why did Einstein say that there is no way of finding out (besides tidal effects) the difference ...
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### How do buoyancy control devices (BCD) work?

I get that having more air decreases density and increases buoyancy. However, we can take the diver-BCD-oxygen-tank to be a single system. How can the pumping of air from the tank into a vest around ...
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### Archimedes Principle [closed]

A block of wood floats in a beaker of water. The block experiences an upward buoyant force. If the beaker (with water and block) is weighed, would the measured weight be less than the sum of the ...
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### Calculus formulas for buoyant force? [duplicate]

I am launching a high-altitude balloon as a part of a physics project I am working on. I know that the amount of helium I need corresponds to about 40 newtons of lift for the launch, which is all I ...
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### Relation between Upthrust and Newtons Law [closed]

Using Newton's $2nd$ law of motion, show that when an object floats on the surface of water, the upthrust experienced by the object and the weight of object must be equal? The first thing is I don't ...
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### Using water pressure as pushing force in a floating bath tub? [closed]

Does physics allow for water pressure to work in this way? if so What formula can prove this? (backup link 1, backup link 2)
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### Understanding Density and the Buoyant Force

A beaker of water resting on a scale registers a weight of 0.61 N. Lowering a steel cube completely into the water (without making any contact with the beaker) causes the reading on the scale to ...
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### Why does the gravitational potential energy decreases as balloon filled with hydrogen ascends up?

As body ascends height increases from the formula $mgh$ the increasing height should increase magnitude of P.E. but some say we should take height negative as it is going up against gravity.
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### Equation of motion for ice block in water

I need to derive the equation of motion for an building block of ice that swims in water. The building block has an initial height that is looking out of the water called $h_A$ and is pushed into the ...
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### What is the energy source if a tall water tank is used to transfer floating objects upwards instead of cables with motors?

Suppose I want to transport some logs from the ground to the roof of a tower. Originally I can use a lift, or some cables, or even move the logs upwards manually; then the energy is converted to the ...
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### Center of Buoyancy

Why does center of buoyancy change when a solid body is rotated along its axis of rotation? Center of mass does not change but why does center buoyancy change which further leads us to the concept ...
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### hot air balloon and pv=nrt [duplicate]

[on hold] up vote-3down votefavorite A hot air balloon has a total mass 750 kg (not including the air in the balloon) and holds a volume of 2.8x10^6 L of air. Assume the density of air outside the ...
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### How to keep a helium balloon between 1 to 5 meters above ground? (without it being tied)

I understand that helium balloons rise because their density is less than air, so they can rise up to a point where the air surrounding it has the same weight as the balloon. I was thinking to fill it ...
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### Can u explain below diagram is possible or not [closed]

If I takes 3 balloons with same size they r connected with same thred frist end have 2 balloons and second end have 1 balloon I put same manner as shown in diagram then frist end is gos up or not or ...
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### I m just try to make Free energy using buoyancy [duplicate]

Can I make power (electricity ) using buoyancy see diagram. if this diagram is possible then how much power i get . I just need formula for upwards speed.
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### Is Buoyant force a reaction?

When we fall on water. The surface molecules are pushed down and as a consequence molecules below the surface molecules and molecules beneath them and so on are also pushed down. Some of them are ...
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### Weighing a baloon

I know of methods of measuring the mass of a gas using chemistry, but this is unrelated. I was wondering if it is possible to deduce the mass of a helium balloon by measuring its mass it on a scale ...
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### Doubt in the concept of Upthrust and Buoyancy

First of all, we know that $P = hρg$ for any depth h in a liquid. While deriving this formula we use (mg + P1A) - P2A = 0, where P1 and P2 are pressures on the upper and lower surfaces respectively. ...
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### Why do helium balloons rise and fall?

I understand why a regular party balloon filled with helium falls over time due to leakage of the helium. However I've also noticed that recently filled helium balloons put outside rise and fall. At ...
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### Physics:Buoyant force and scale readings

Sorry this might seem like a dumb question, but I'm having trouble understanding the concept behind buoyant force and scale readings. Suppose I have a beaker filled with water, and the beaker is ...