Possible title: How Does Water Affect the Force on a Metal Cube in a Vessel?

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Discussion Overview

The discussion revolves around the effects of water on the force exerted by a metal cube placed in a vessel, specifically addressing the differences in force when the cube is in air versus when it is fully immersed in water. The scope includes conceptual reasoning and technical explanations related to buoyancy and pressure.

Discussion Character

  • Conceptual clarification
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant asserts that the force on the bottom of the vessel remains the same when the cube is immersed in water, questioning how this could be the case given the buoyant force.
  • Another participant presumes that the water level is up to the top of the cube without covering it, suggesting that this affects the contact with the vessel's bottom.
  • A participant raises a doubt regarding the force exerted by the cube, proposing that it should vary between the two cases due to differences in fluid density, specifically comparing air and water.
  • Another participant echoes the concern about the varying force based on fluid density and asks for a more detailed description of the situation, questioning why the presence of water would increase the pressure exerted by the cube on the bottom.
  • A later reply discusses the downward force due to gravity remaining constant and explains how buoyancy is determined by pressure differences, while also noting practical challenges such as the potential for a micro layer of water affecting the force exerted by the cube.

Areas of Agreement / Disagreement

Participants express differing views on how the presence of water affects the force exerted by the cube, with some questioning the initial assertion that the force remains unchanged. The discussion remains unresolved, with multiple competing perspectives on the impact of buoyancy and fluid density.

Contextual Notes

Participants have not fully defined the assumptions regarding the contact between the cube and the vessel's bottom, nor have they resolved the implications of buoyancy in this scenario. The discussion also lacks clarity on the conditions under which the water interacts with the cube.

Cromptu
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A metal cube is placed in an empty vessel. When water is filled in the vessel so that the cube is completely immersed in the water, the force on the bottom of the vessel in contact with the cube :

Ans: Will remain the same.

But how? Won't the force exerted in the second case,i.e when the vessel is filled with water be less because of the buoyant force?


Please help!
 
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Presumably: There is no water layer beneath the cube, so it remains in direct contact with the surface of the vessel. And the water level is just up to the top of the cube, but does not cover it.
 
I have another doubt.
The force which the cube will exert on the bottom will be equal to : pressure*area , i.e., (height*density*gravitational acceleration) * area of the bottom.
Won't this force vary in the two cases? where in case 1, air is the fluid(density almost negligible) and in case 2 water is the fluid (much more dense)
 
Cromptu said:
I have another doubt.
The force which the cube will exert on the bottom will be equal to : pressure*area , i.e., (height*density*gravitational acceleration) * area of the bottom.
Won't this force vary in the two cases? where in case 1, air is the fluid(density almost negligible) and in case 2 water is the fluid (much more dense)
You're going to have to describe the situation in more detail. (See the presumptions of my last post.) Assuming that the water does not cover the cube, why would the presence of the water increase the pressure that the cube exerts on the bottom?
 
(height*density*gravitational acceleration) * area

This is the downward force due to gravity: F=mg. It stays constant.
The upward force due to buoyancy is obtained from the pressure difference between the top and the bottom of your object. The density on the bottom of your solid is the density of the 'floor'. The density on the top is the density of air. These stay the same, regardless of any density changes at the sides of the cube.

In practice however, it will be difficult to prevent the occurrence of a micro layer of water between the solid and the floor. As soon as the solid is detached from the floor, you will get buoyancy.
 

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