What will be the weight measured by the balance?

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Discussion Overview

The discussion revolves around the effects of immersing a solid block in a beaker of water on the reading of a weighing machine or spring balance. Participants explore the implications of buoyancy and forces acting on the block in different scenarios, including whether the block touches the beaker or not. The scope includes conceptual reasoning and technical explanations related to forces and weight measurement.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested
  • Homework-related

Main Points Raised

  • Some participants propose that immersing a solid block in water will increase the weight reading on the balance because the total mass of the system changes.
  • Others argue that the reading may not change since the block does not touch the walls or bottom of the beaker, suggesting that the buoyant force may counteract the weight increase.
  • A participant mentions the importance of free body diagrams to analyze the forces acting on the block before and after immersion.
  • There is a discussion about the forces acting on the block, including gravity and buoyant force, and how these forces interact when the block is submerged.
  • Some participants express uncertainty about whether the reading will change, indicating that the problem's conditions are not fully specified.

Areas of Agreement / Disagreement

Participants do not reach a consensus on whether the reading of the balance will increase or remain the same upon immersion of the block. Multiple competing views remain regarding the effects of buoyancy and the conditions of the experiment.

Contextual Notes

Limitations include the lack of clarity on specific conditions of the experiment, such as whether the beaker overflows and the exact nature of the materials involved (e.g., stone, iron, cork).

donaldparida
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Suppose there is a beaker filled with water placed on a weighing machine. Suppose the reading is x kg. Now, if i immerse a solid block inside the beaker without touching the walls or the bottom of the beaker, will the reading given by the weighing machine increase or not?
 
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Depends ... give us the complete statement of the problem.
 
Actually the problem was like this:
A beaker containing water is suspended from a spring balance. Does the reading of the spring balance change
(a)When a piece of stone suspended from a string is immersed in water without touching the beaker?
(b)When a piece of iron or cork is put in water in the bucket?
 
donaldparida said:
Suppose there is a beaker filled with water placed on a weighing machine. Suppose the reading is x kg. Now, if i immerse a solid block inside the beaker without touching the walls or the bottom of the beaker, will the reading given by the weighing machine increase or not?

Initially you have mass of x Kg which represents beaker filled with some water...now you are having beaker +water +mass(immerged) so mass has changed therefore it should show some increase in the weight of the new system on the pan...but i wish to know from you the reason behind raising this question...
my guess is that you may be thinking that the liquid/water is supporting the mass so that how it will effect the weight...then you may imagine yourself standing on the weighing machine and then drink a litre of juice ...should the weight increase or not?
 
@drvrm I asked this question because intuitively it seems to me that there should not be any rise in the reading of the balance since the object does not touch the walls of the beaker.
 
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Yes.
 
Draw a free body diagram of the stone before and after immersion. What do you notice?
 
Before immersion the force acting on the body is the force of gravity and the force exerted by us to balance the force of gravity and after immersion the force acting on the stone is the force of gravity, the force exerted by us to balance the force of gravity and the buoyant force exerted by the water.
 
  • #10
donaldparida said:
filled
Does it overflow?
donaldparida said:
stone suspended from a string
You've still got "no change/increase/decrease" possibilities.
donaldparida said:
iron or cork
 
  • #11
It may or it may not. That is not mentioned.
 
  • #12
donaldparida said:
Before immersion the force acting on the body is the force of gravity only and after immersion the force acting on the stone is the force of gravity as well as the buoyant force exerted by the water.
Good, I think you have it from here.

For future reference, please post homework questions in the appropriate forum:
https://www.physicsforums.com/forums/introductory-physics-homework.153/
 

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