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.
Questions tagged [buoyancy]
665 questions
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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 the lake. What happens to the water level in the…
lezebulon
- 453
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votes
3 answers
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 action, and my first thought was that if the air from…
ColinM
- 181
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3 answers
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 different substances and identical balloons?
I am…
naonam
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Dropping an anchor from a boat
A yacht on a lake drops its anchor overboard. What happens to the water level in the lake?
It rises very slightly.
It falls very slightly.
It stays exactly the same.
It's impossible to say.
My understanding is that due to Archimedes principle,…
Thomas Russell
- 1,194
6
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2 answers
Why do people only float in certain orientations?
If the buoyant force on an object is equal to the weight of the water displaced by the object, why do people have an easier time floating on their back than vertically with their head sticking out of the water?
Bassinator
- 263
6
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2 answers
Why does density decide whether something floats or sinks?
Possible Duplicate:
Balloons and lifting gases
I know that the density of an object dictates whether or not it will float, but why?
My idea is: an object with a lower density has a spread out mass distribution. Since water's density is 1…
Curiousman
- 253
5
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2 answers
A man on a boat, with something in his hand
Possible Duplicate:
Basic buoyancy question: Man in a boat with a stone
A man is on a boat, in the middle of a quiet lake.
He has something in his hands (anything you like)
He throws the "something" in the water.
Does the water level increases or…
5
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4 answers
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, and I was reminded of the…
Jason S
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1 answer
Why is the force acting down on an object submerged in a fluid only equal to the force of gravity?
I was reading through a solution to the following problem:
What acceleration will a completely submerged object experience if its density is three times that of the fluid in which it is submerged?
The solution states $F_\text{down} -…
user3002473
- 175
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6 answers
Cause of buoyant force?
Can you explain to me what causes the buoyant force? Is this a result of a density gradient, or is it like a normal force with solid objects?
user15532
4
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4 answers
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, how come we observe such an effect?
osman
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Buoyancy force on object between three liquids
I have a thought experiment.
Suppose you have 3 layers of liquid resting on each other in a beaker. A long cylinder of some material is placed in the beaker so that it passes through all layers of liquid. My question is if the middle layer of liquid…
FizzleDizzle
- 383
3
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4 answers
Why does suspending a dense weight in a water-filled beaker make it heavier?
I was pondering Which way does the scale tip? I understand it tips to the right. Here's the setup:
The issue is my intuition fails in understanding what happens on the right side. If I place a beaker with water on a scale, it will measure some…
Phil Frost
- 4,161
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What will happen to a ball suspended in a liquid if we create air bubbles underneath it?
Suppose we have a cylinder half filled with water and a ping-pong ball, floating on the surface. We cut small holes in the bottom of the cylinder and proceed to blow air through it, resulting in air bubbles forming and rising up.
Now, I have to note…
neverneve
- 763
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1 answer
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 able to come up with a general formula for this.…
Gerard
- 2,730