What will be the weight measured by the balance?

In summary, the conversation discusses the potential change in weight on a weighing machine when a solid block is immersed in a beaker filled with water. The group considers factors such as buoyancy and free body diagrams to determine that the reading on the weighing machine should increase due to the added mass of the immersed object. The conversation also mentions the possibility of overflow, but does not provide enough information to determine if it will occur. Lastly, it is recommended that future homework questions be posted in the appropriate forum for assistance.
  • #1
donaldparida
146
10
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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  • #2
Depends ... give us the complete statement of the problem.
 
  • #3
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?
 
  • #4
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?
 
  • #5
@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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  • #7
Yes.
 
  • #8
Draw a free body diagram of the stone before and after immersion. What do you notice?
 
  • #9
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/
 

1. What is the purpose of using a balance to measure weight?

The purpose of using a balance to measure weight is to accurately determine the mass of an object. This is important in many scientific experiments and industries where precise measurements are necessary.

2. How does a balance measure weight?

A balance measures weight by comparing the force of gravity on the object being weighed to the force of gravity on a known mass. This is done by using a calibrated scale and a pan to hold the object being weighed.

3. What is the difference between mass and weight?

Mass is a measure of the amount of matter in an object, while weight is a measure of the force of gravity on an object. Therefore, weight can change depending on the strength of gravity, while mass remains constant.

4. Can a balance measure weight in different units?

Yes, a balance can measure weight in different units such as grams, kilograms, or pounds. However, the balance must be properly calibrated and the correct unit must be selected before weighing an object.

5. Is the weight measured by a balance always accurate?

The weight measured by a balance can be accurate if the balance is properly calibrated and used correctly. Factors such as air resistance and the location of the balance can affect the accuracy of the measurement.

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