Relative weights in air and water

In summary, two solid pieces made of steel and aluminium have equal weights when completely immersed in water. However, when weighed in air, the aluminium piece appears to weigh more. This can be explained by applying Archimedes' Principle, which states that the weight of an object in air minus its weight in liquid is equal to the upthrust experienced. Since the weight in liquid is the same for both pieces, the difference in weight in air is due to the difference in upthrust experienced by each object. Without information about the volume or upthrust, it is difficult to determine the exact factors that influence this difference. However, by creating symbols for the unknown densities and volumes and using relevant equations, further deductions can be made.
  • #1
ScifiGen
5
0

Homework Statement


Two solid pieces, one of steel and the other of aluminium when completely immersed in water have equal weights. When these solid pieces are weighed in air, aluminium seems to weigh more. Why is this so? On what factors in this being decided?[/B]

Homework Equations

The Attempt at a Solution

 
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  • #2
ScifiGen said:

Homework Statement


Two solid pieces, one of steel and the other of aluminium when completely immersed in water have equal weights. When these solid pieces are weighed in air, aluminium seems to weigh more. Why is this so? On what factors in this being decided?[/B]

Homework Equations

The Attempt at a Solution

You need to show an attempt at a solution.

What do you know? Where are you stuck?
 
  • #3
SammyS said:
You need to show an attempt at a solution.

What do you know? Where are you stuck?
The relevant principle , I think , is the Archimedes' Principle.
According to it, weight in air-weight in liquid=Upthrust experienced.
Weight in liquid is the same for both, There is no information about volume or upthrust experienced of the solids.
So, I'm pretty much stuck too...
 
  • #4
There is no information about volume or upthrust experienced of the solids.
There is some information in the given
When these solid pieces are weighed in air, aluminium seems to weigh more
which -- when properly dealt with in your relevant equation -- can help you further.
 
  • #5
It might help if you create symbols for the unknown densities and volumes of the two objects. You can then express the facts you are given as equations and inequalities and see what you can deduce.
 

1. What is the difference between relative weights in air and water?

The relative weight of an object in air is its weight when measured in a vacuum, while the relative weight in water is its weight when submerged in water. This is because the buoyant force of water affects the weight of an object when it is submerged.

2. How is the relative weight of an object affected by its density in air and water?

The relative weight of an object in air and water is directly proportional to the object's density. Objects with a higher density will have a greater relative weight in both air and water, while objects with a lower density will have a lower relative weight.

3. Why is the relative weight of an object in water less than in air?

The buoyant force of water acts in the opposite direction of gravity, which decreases the effective weight of an object when it is submerged. This is why an object will have a lower relative weight in water compared to in air.

4. How is the relative weight of an object in water affected by its shape?

The shape of an object does not affect its relative weight in water. However, the shape can impact the amount of water displaced and therefore affect the buoyant force acting on the object.

5. How can the relative weight of an object in air and water be measured?

The relative weight of an object in air can be measured using a standard scale, while the relative weight in water can be measured by using a scale while the object is submerged in water. The difference between the two measurements will give the relative weight in water.

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