Quiz Question -- What happens to the cork?

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Discussion Overview

The discussion revolves around a physics problem involving a cork floating in a glass of water that is dropped in free fall. Participants explore the motion of the cork relative to the glass wall during the fall, considering the effects of buoyancy and the spring tension attached to the cork.

Discussion Character

  • Exploratory
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant describes the initial setup, noting that the cork is pulled deeper into the water by a spring, which increases the buoyant force acting on it.
  • Another participant suggests that during free fall, the buoyant force becomes negligible, leading to the conclusion that the spring will return to its relaxed position, causing the cork to move downward.
  • Several participants assert that the cork will move downward due to the internal spring force being the only force acting on it in free fall.
  • One participant emphasizes that the water may drift out of the glass, further supporting the idea that the cork will descend to the relaxed position of the spring.

Areas of Agreement / Disagreement

Participants generally agree that the cork will move downward during free fall, but the reasoning behind this conclusion varies among them. There is no consensus on the detailed mechanics involved.

Contextual Notes

Some assumptions regarding the behavior of the water and the spring's properties during free fall remain unaddressed, and the discussion does not resolve the exact dynamics of the cork's motion.

Who May Find This Useful

This discussion may be of interest to those studying fluid dynamics, mechanics, or anyone curious about the effects of buoyancy and forces in free fall scenarios.

zul8tr
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You have a glass of water with a cork floating in it. The cork is attached by a spring under some tension that is also attached to the bottom of the glass so the cork is slightly pulled deeper in the water than just by its own weight thus the cork has a bit more buoyant force. The cork always remains centered in the glass.
If the glass is dropped free fall and remains vertical and no water spills out what motion does the cork do relative to the glass wall, obviously before it hits the ground? Go up, down, remain the same and why?
 
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zul8tr said:
You have a glass of water with a cork floating in it. The cork is attached by a spring under some tension that is also attached to the bottom of the glass so the cork is slightly pulled deeper in the water than just by its own weight thus the cork has a bit more buoyant force. The cork always remains centered in the glass.
If the glass is dropped free fall and remains vertical and no water spills out what motion does the cork do relative to the glass wall, obviously before it hits the ground? Go up, down, remain the same and why?
What do YOU think happens and why? :smile:
 
I know the answer wouldn't want to give it away too soon, needs others to solve.
 
Thread closed for Moderation. We often do not allow quiz questions like this because they could be disguised homework assignments. Given you user Profile, I doubt it is homework. Please start a private conversation with me (click my avatar and "Start a Conversation") and let me know your solution. If it looks good, I can re-open the thread.
 
Thank you for the PM and for your patience. Thread is re-opened as a Quiz Question. :smile:
 
In the free fall there is no buoyant force, so the spring should go back to the zero position, and the cork will of course go downward as the spring pulls it down. Good question @zul8tr . I answered quickly without giving it very careful analysis, but I think I may have gotten the correct answer. :)
 
Down.
 
Down to the relaxed position of the spring, a conclusion that will be altogether natural if you consider that the water will tend to drift out the glass leaving the spring behind.
 
Down is the correct reaction of the cork. Internal spring force is all that is acting on the cork, free fall has reduced buoyancy to zero
 
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