Yes, that makes sense. Thank you for pointing that out.

In summary: BTW, I missed this before. The mass of 1L of water is 1kg. To get the weight in Newtons, you need to multiply the mass by the acceleration of gravity. Makes sense?Yes, that is correct.
  • #1
ztf24
5
0

Homework Statement

- [/B]

What is the buoyant force that acts on a fully submerged 1-L bottle of water? What is the buoyant force that acts on it if it is full of air, not water, but is still fully submerged? Assume you'd have to hold it under water.

Homework Equations

- [/B]Fb= V x D x G

The Attempt at a Solution

-
[/B]
I know the volume is 1L, and G is 9.8 M/S. I'm unsure with the density therefore I can't get an answer.
 
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  • #2
ztf24 said:

Homework Statement

- [/B]

What is the buoyant force that acts on a fully submerged 1-L bottle of water? What is the buoyant force that acts on it if it is full of air, not water, but is still fully submerged? Assume you'd have to hold it under water.

Homework Equations

- [/B]Fb= V x D x G

The Attempt at a Solution

-
[/B]
I know the volume is 1L, and G is 9.8 M/S. I'm unsure with the density therefore I can't get an answer.
Welcome to the PF.

The density of fresh water is well known. What is the mass of each cc of water?

Assuming that the glass portion of the bottle is negligible, when it is filled with water and is underwater it's just like drawing a box around a piece of water -- that water does not go up or down, so what is the net force on it?

When the bottle is filled with air instead, how much does it weigh?
 
  • #3
berkeman said:
Welcome to the PF.

The density of fresh water is well known. What is the mass of each cc of water?

Assuming that the glass portion of the bottle is negligible, when it is filled with water and is underwater it's just like drawing a box around a piece of water -- that water does not go up or down, so what is the net force on it?

When the bottle is filled with air instead, how much does it weigh?
Densiry of Water is 1g/CM 3 and the liter of water weighs 1KG
 
  • #4
ztf24 said:
Densiry of Water is 1g/CM 3 and the liter of water weighs 1KG
Correct. So how can you use that and the concepts of Buoyancy to answer this set of questions?

https://en.wikipedia.org/wiki/Buoyancy

:smile:
 
  • #5
berkeman said:
Correct. So how can you use that and the concepts of Buoyancy to answer this set of questions?

https://en.wikipedia.org/wiki/Buoyancy

:smile:
I guess I'm lost. I don't even know if need an equation for this problem. My guess is the buoyancy force is greater when the bottle is filled with water, and not air.
 
  • #6
ztf24 said:
I guess I'm lost. I don't even know if need an equation for this problem. My guess is the buoyancy force is greater when the bottle is filled with water, and not air.
Did you read over the Wikipedia link?

I suppose it depends a bit on how your textbook defines "buoyant force". There will always be a buoyant force, but in one case it is counteracted by the weight of the water in the bottle, and in the other case it is not (when the bottle if filled with air). In the first case the bottle has no Net force on it, but in the 2nd case, there is a strong Net force which direction?

EDIT -- fixed a bunch of typos in my post...
 
  • #7
berkeman said:
Did you read over the Wikipedia link?

I suppose it depends a bit on how your textbook defines "buoyant force". There will always be a buoyant force, but in one case it is counteracted by the weight of the water in the bottle, and in the other case it is not (when the bottle if filled with air). In the first case the bottle has no Net force on it, but in the 2nd case, there is a strong Net force which direction?

EDIT -- fixed a bunch of typos in my post...
There's an upward net force on the bottle
 
  • #8
Read what this link says about Archimedes' principle. That will tell you how to calculate the buoyant force.
 
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  • #9
ztf24 said:
Densiry of Water is 1g/CM 3 and the liter of water weighs 1KG
BTW, I missed this before. The mass of 1L of water is 1kg. To get the weight in Newtons, you need to multiply the mass by the acceleration of gravity. Makes sense?
 

Related to Yes, that makes sense. Thank you for pointing that out.

What is buoyant force?

Buoyant force is the upward force exerted by a fluid on an object that is partially or completely submerged in the fluid. It is also known as Archimedes' principle.

How is buoyant force calculated?

Buoyant force is calculated by multiplying the density of the fluid, the acceleration due to gravity, and the volume of the fluid displaced by the object.

What are some real-life examples of buoyant force?

Some common examples of buoyant force include why objects float in water, why hot air balloons rise, and why helium balloons float in the air.

How does the shape and density of an object affect buoyant force?

The shape and density of an object both play a role in determining the buoyant force acting on it. Objects with a greater volume and lower density will experience a greater buoyant force, while objects with a smaller volume and higher density will experience a smaller buoyant force.

How can buoyant force be used in everyday life?

Buoyant force has many practical applications, such as in shipbuilding, designing life jackets and other flotation devices, and creating submarines. It is also used in industries such as oil and gas to lift heavy structures to the surface of the water.

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