I have a free body diagram that I have drawn to describe my problem of dry ice in a bottle

In summary, the free body diagram illustrates the forces acting on a bottle containing dry ice, highlighting the pressure buildup and potential risks associated with sealing the container.
  • #1
tremain74
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Homework Statement
I have a problem where you have a plastic bottle of dry ice. As you put warm water into the bottle, dry ice is converted into dry ice. I want to see if my free body diagram makes any kind of logical sense.
Relevant Equations
I used Newton's second law of motion: Force = mass * acceleration.
This is my attached picture.

PXL_20240522_235104888.jpg
 
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  • #2
tremain74 said:
dry ice is converted into dry ice
Doesn't sound like a very interesting conversion. The process would be "do nothing".
 
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  • #3
phinds said:
Doesn't sound like a very interesting conversion. The process would be "do nothing".
Actually, I meant that the dry ice is converted into carbon dioxide. My apology.
 
  • #4
A water-iceberg, floating in a liquid sea of salt solution, is converted into a smaller iceberg, and a more dilute, cooler liquid ocean.

A dry-iceberg floating in warm water, is converted into CO2 that escapes, and cooler water that eventually may partly freeze, then thaw.
The more dense CO2 gas, first displaces the air, then overflows the bottle.
The dry-iceberg cannot be coated in water ice, because that is pushed off by the CO2 sublimed.

Is your FBD modelling icebergs, that are changing their mass by melting or subliming, while floating and being buoyant in changing density fluids?
 
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  • #5
Baluncore said:
A water-iceberg, floating in a liquid sea of salt solution, is converted into a smaller iceberg, and a more dilute, cooler liquid ocean.

A dry-iceberg floating in warm water, is converted into CO2 that escapes, and cooler water that eventually may partly freeze, then thaw.
The more dense CO2 gas, first displaces the air, then overflows the bottle.
The dry-iceberg cannot be coated in water ice, because that is pushed off by the CO2 sublimed.

Is your FBD modelling icebergs, that are changing their mass by melting or subliming, while floating and being buoyant in changing density fluids?
My free body diagram doesn't include the ice that comes as a result of water that will eventually freeze. However, in reality, I definitely have to include the ice in the fbd as well.
 
  • #6
tremain74 said:
However, in reality, I definitely have to include the ice in the fbd as well.
A wet ice lump, floating in a glass of cold water, will gradually melt, but the water level in the glass will stay practically the same throughout the process.

Big bits of dry ice sink in water. Small bits also sink, but then float as they sublime, as they are buoyed up by the attached gas bubbles. A fog will form near the surface of the water. Your FBD will need a little more complexity.

Maybe you should first decide why you need an FBD, or what you are trying to model.
 
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FAQ: I have a free body diagram that I have drawn to describe my problem of dry ice in a bottle

What is a free body diagram, and how is it used in this context?

A free body diagram is a graphical representation that shows all the forces acting on an object. In the context of dry ice in a bottle, it helps visualize the forces such as pressure, gravity, and any other external forces acting on the bottle and its contents. This can help in analyzing the physical behavior of the system, such as the potential for pressure build-up and the effects of temperature changes.

What forces should I include in my free body diagram for dry ice in a bottle?

You should include the following forces in your free body diagram: the gravitational force acting downward on the bottle and dry ice, the pressure force exerted by the gas produced from the sublimation of dry ice, and any external forces such as atmospheric pressure acting on the bottle's surface. If the bottle is being held or manipulated, you may also want to include forces from human interaction.

How does the sublimation of dry ice affect the forces in my diagram?

The sublimation of dry ice (solid carbon dioxide) produces carbon dioxide gas, which increases the internal pressure within the bottle. This gas generation creates an upward force that can be represented in your free body diagram. As the gas builds up, it can lead to an increase in pressure that may eventually exceed the structural limits of the bottle, which is crucial to analyze for safety reasons.

What safety considerations should I keep in mind when analyzing dry ice in a bottle?

When analyzing dry ice in a bottle, it is essential to consider the risk of pressure build-up due to gas generation. Ensure that the bottle is not sealed tightly to allow gas to escape, as this can prevent explosions or ruptures. Additionally, handle dry ice with gloves to avoid frostbite, and ensure proper ventilation to avoid the accumulation of carbon dioxide gas, which can be hazardous in confined spaces.

Can I use this free body diagram for other scenarios involving gases and pressure?

Yes, the principles illustrated in your free body diagram can be applied to other scenarios involving gases and pressure. For example, similar diagrams can be used for understanding the behavior of gases in closed containers, the effects of temperature changes on gas pressure, and the dynamics of gas expansion in various systems. The fundamental concepts of force analysis remain consistent across different applications.

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