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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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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2answers
29 views

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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34 views

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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2answers
44 views

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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1answer
31 views

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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43 views

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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1answer
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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 ...
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2answers
43 views

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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3answers
37 views

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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1answer
103 views

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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1answer
29 views

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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1answer
48 views

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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1answer
47 views

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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2answers
67 views

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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1answer
125 views

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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2answers
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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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1answer
37 views

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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2answers
85 views

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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0answers
51 views

Calculus formulas for buoyant force?

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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1answer
50 views

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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1answer
108 views

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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2answers
93 views

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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2answers
93 views

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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4answers
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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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7answers
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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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1answer
63 views

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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49 views

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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2answers
59 views

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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1answer
62 views

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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1answer
185 views

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 ...
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2answers
133 views

Why buoyancy is applied on centroid?

My book says: "The point of application of the buoyancy force is the geometric center(centroid) of the submerged part of the body, whereas the specific gravity of the fluid is constant." But why ...
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1answer
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Permanent flying balloon

We all know balloons which are filled with gas that's less dense than air. After a few hours, the balloon drops to the ground. The reason for this phenomenon, as far as i understand, is that the ...
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1answer
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Why does the water level go down when a dense object is moved from a boat to the bottom of the pool [duplicate]

Imagine you have a container ship with an extremely heavy mass on it. Why does the water level on the ship drop when the mass is placed in water?
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Is the reason why water in a cup rises if a solid is placed within it the ideal gas law?

Let's say you have a cylinder with water that takes up volume V and has temperature T. When a solid mass is placed within the cylinder, the water momentarily takes up a smaller volume within the ...
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1answer
71 views

A pure water ice cube with sides 2cm long floats in a liquid in a glass beaker [duplicate]

A pure water ice cube with sides $2\,\mathrm{cm}$ long floats in a liquid in a glass beaker. What volume will be below the liquid surface if the liquid is a) pure water and b) brine? ...
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2answers
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Would the level of the water be rising, falling, or staying the same? [duplicate]

one day you were standing on the shore of a small lake. you looked out onto the water and saw a boat. in the boat were two men with five huge steel beams. the men were sidling the beams out of the ...
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2answers
528 views

How come a cork float to the side of a glass? [duplicate]

There's a not-so-recent video by a user named quirkology here, where he shows bets that usually work. From @2:19, he puts a wine bottle cap at the center of a glass ...
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0answers
33 views

How to calculate the depth of a flow meter so that there are no air bubbles in the stream

A mix of air and water (foam) is flowing into a tank from the left and going out to the right. To the right there is a suction pump. The tank is divided by a middle vertical wall that stretches from ...
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1answer
68 views

Making sense of the Buoyancy force [duplicate]

I was reading about how to find the buoyancy force when I came across this explanation: Imagine a box submerged in a tank of liquid. The distance from the surface of the liquid to the bottom ...
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1answer
87 views

If the surface tension is reduced to half(say by using a surfactant), what would be the effect on the size of an air bubble in the liquid

If I reduce the surface tension to half of the original value, what would be the effect on the size of an air bubble in the fluid? What would be the effect on buoyancy and drag forces? Also, if I ...