How Does the Weight of Stainless Steel Change in Sea Water?

In summary, a bolt of stainless steel weighing 13 kg in air would have the weight equivalent of 11.3 kg when immersed in seawater of density 1025 kg/m3, according to Archimedes' principle. This means that the buoyant force is equal to the weight of the fluid displaced by the object, resulting in a lighter weight in water compared to air. There may be some confusion regarding the use of kilograms as a unit of weight, as technically it is a unit of mass. However, the calculation is still valid.
  • #1
TorMcOst
9
0
I have a bolt (13 kg) of stainless steel (1650 cm``). How much will this weight in sea water?

Thank you in advance!
 
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  • #2
You should be able to use Archimedes principle. The buoyant force is equal to the weight of fluid displaced by the object. Calculate the weight of the volume of equivalen seawater and subtract that off I believe.
 
  • #3
Thanks a lot for your respond Born2bwire!

This means that my calculation will become something like this:

Weight in Air: 13,000 kg
- Weight of fluid displaced (1650 cm3*1,025): 1,691 kg
= Weight in Sea Water: 11,309 kg

Correct?
 
  • #4
Yeah, that's how I would work it. We'll see if anyone here ends up disagreeing.
 
  • #5
TorMcOst said:
Thanks a lot for your respond Born2bwire!

This means that my calculation will become something like this:

Weight in Air: 13,000 kg
- Weight of fluid displaced (1650 cm3*1,025): 1,691 kg
= Weight in Sea Water: 11,309 kg

Correct?
Does one mean 13 (13.000) kg, or perhaps 13,000 g? kg (g) is a unit of mass, N (Newton) or dyne (used in cgs system) is a measure of weight. Mass * acceleration of gravity would give weight (force) due to gravity.

The apparent mass in seawater would be 11.309 kg (11,309 g). The application of Archimedes principle (buoyancy) is correct.

In English units, one will find pounds mass (lbm) and pounds force (lbf), but strictly speaking they are not the same.
 
  • #6
Thanks Astronuc!

However I got a little confused. By 13,000kg I meant 13 kg (in air). And my following answer was that this bolt would weight 11,3kg in water. Do you agree or disagree with this calculation?
 
  • #7
TorMcOst said:
Thanks Astronuc!

However I got a little confused. By 13,000kg I meant 13 kg (in air). And my following answer was that this bolt would weight 11,3kg in water. Do you agree or disagree with this calculation?

He doesn't like your use of kilograms as a unit of weight. Technically, kilogram is a unit of mass, Newtons would be an appropriate unit of weight.
 
  • #8
TorMcOst said:
Thanks Astronuc!

However I got a little confused. By 13,000kg I meant 13 kg (in air). And my following answer was that this bolt would weight 11,3kg in water. Do you agree or disagree with this calculation?
As Born2bwire indicated, I was referring to the use of mass as weight. Being a physics forum, we wish to be accurate in such a matter.

I agree with the calculation that 13 kg of steel as described would have the weight equivalent of 11.3 kg (as measured in air), when the steel is immersed in seawater of density (1025 kg/m3), i.e. it appears lighter in water than it would in air.
 
  • #9
Cheers Astronuc and Born2bwire, this have been to great help for me! And for the record, I will try to be more accurate in my physics from now on!
 

1. What is the corrosion resistance of stainless steel in sea water?

Stainless steel is highly corrosion resistant in sea water due to its chromium content, which forms a protective oxide layer on the surface of the steel. This layer prevents further corrosion and makes stainless steel suitable for use in marine environments.

2. Can stainless steel be used in sea water without any coatings or treatments?

Yes, stainless steel can be used in sea water without any additional coatings or treatments. Its inherent corrosion resistance makes it a popular choice for marine applications.

3. Are there different types of stainless steel that are more suitable for use in sea water?

Yes, there are different types of stainless steel that are specifically designed for use in marine environments. These include types 316 and 316L, which have higher levels of molybdenum and nickel for improved corrosion resistance.

4. Does the temperature of the sea water affect the corrosion resistance of stainless steel?

Yes, the temperature of the sea water can affect the corrosion resistance of stainless steel. Higher temperatures, especially in the presence of chloride ions, can increase the rate of corrosion. Therefore, it is important to consider the temperature of the water when selecting the appropriate type of stainless steel for a marine application.

5. How can I maintain the corrosion resistance of stainless steel in sea water?

To maintain the corrosion resistance of stainless steel in sea water, regular cleaning and maintenance is recommended. This includes removing any marine deposits or biofilms that may form on the surface of the steel. Additionally, using higher grades of stainless steel and avoiding exposure to harsh chemicals can also help prolong the lifespan of the steel in sea water.

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