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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Calculate the stable height of a balloon

My son has asked me a question, and I'm afraid my high school maths are not up to the task: Is it possible to calculate the height that a given balloon (filled with a known quantity of helium) will ...
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Buoyancy in gases

If buoyancy is caused by pressure gradient and if the pressure of a gas is same everywhere in its container, which means there's no difference of pressures on surfaces of the lighter-than-air object, ...
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Infinite Energy from Bobbing

Could this device theoretically continue in motion forever? If not, why not? (click below for images): Device description. Device process. The device is less dense than air, so it rises. The ...
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In hydrostatics, is it possible for the bouancy to be greater than the weight of a body?

In the diagram we have two bodies, with density and volume $\delta$ and $V$, and a fluid $\ell$. $$\delta_1=0,7 \rm\frac{gr}{cm^3}$$ $$\delta_2=2 \rm\frac{gr}{cm^3}$$ $$V_1=100 \rm {cm^3}$$ $$V_2=10 ...
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Basic buoyancy question: Man in a boat with a stone

This comes from a brain teaser but I'm not sure I can solve it: You are in a rowing boat on a lake. A large heavy rock is also in the boat. You heave the rock overboard. It sinks to the bottom of ...
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How do we describe the relationship of balloon size and related lift?

We know that hydrogen and helium are lighter that air. Therefore it is certain that they would create a lifting force when enclosed in a balloon. How do we describe the relationship of balloon size ...
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Costa Concordia shipwreck: why can't they right the ship with pingpong balls?

So I guess I don't really understand the situation in question... I heard a radio piece about the Costa Concordia shipwreck in Italy taking 7-10 months to remove the vessel from its place of resting, ...
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How does placing objects in liquids affect the mass?

I was dazing off in my physics class when I came up with this question and I was wondering about it all day. I could not provide myself with an adequate solution, so here I am asking the forum about ...
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Does a Lorentz-contracted object float or sink?

Consider the following thought experiment: Imagine an object of a certain mass density which allows it to float in water. Now if this object is viewed from a moving frame with high speed, it will ...
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Buoyancy experiment with my child

I've read through a few other answers here on buoyancy and I was hoping to get some guidance on discussing it with at 5th grader. So, taking a ball of playdoh clay and dropping it into a container of ...
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Why does density decide whether something floats or sinks? [duplicate]

Possible Duplicate: Balloons and lifting gases I understand that density of an object dictates whether or not it will float, but what I don't get and can't get any satisfactory ...
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Why does an object when filled with water sink, but without water inside float (in a body of water)?

Why does an object sink when filled with water, even if the same object would float without water inside? For example, put an empty glass cup into water, and it floats. But if you put a plastic ...
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Would a submarine float in the atmosphere of Jupiter?

Would a submarine float in the atmosphere of Jupiter, or would it get crushed?
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Buoyancy: helium vs hydrogen balloons

Given I have two identical balloons on earth, how will the buoyancy compare between the one filled with helium and another filled with hydrogen? How can I calculate the ratio of buoyancy given two ...
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“Troll physics”: Buoyancy for infinite power [duplicate]

Possible Duplicate: What is the fallacy in this infinite motion machine? Most of the "troll physics" images I can figure out, but this one has me stumped. What is broken about the following ...
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The Galileo thermometer: why do the bubbles float in the middle of the tube?

If the water were uniform temperature, it would have uniform density, so a bubble should either be all the way at the top (if it's lighter than water) or all the way at the bottom (if heavier). But in ...
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Measuring the spring constant in a system with hydrostatic buoyancy

I have a physics lab tomorrow and I would appreciate it if you could give me your opinion on whether my reasoning is correct for this situation or not: http://i.stack.imgur.com/WMzA7.jpg The title ...
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Counteracting g-force

Is it possible to counter-act g-force for a jet-pilot, by him putting on a scuba-diving suit and filling the cockpit with water? On earth we are constantly pulled down, or accelerated with one g. In ...
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Why do helium filled balloons move away from the Earth?

From my understanding objects do not fall but are pulled to the earth from gravity. With this in mind, I can't understand why if helium filled balloons are not pulled by gravity then shouldn't they ...
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2answers
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Balloons and lifting gases

Hydrogen is the lightest element, so it's cable of lifting the most weight in out atmosphere (probably not the best terminology there, but you get the picture) Would hot hydrogen (in the same sense ...
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What is the fallacy in this infinite motion machine?

I realize this isn't possible, but I can't see why not, especially if you change the model a little bit so that the balls simply travel through a tube of water on the way up, rather than exactly ...
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7answers
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What property of objects allow them to float?

I used to think that the shape of an object determines its ability to float (boat-shaped objects are more likely to float, and spheres tend to sink). But my friend, who is fond of making me look ...