Can body float in water at different depth level..?

Replies

• 

  Ramani Aswath

  Consider a body of water that has a uniform temperature gradient higher at the surface and progressively colder downward. There will be a corresponding density gradient. Any object with a density in between that at the top and at the bottom will float at a point where the density matches.
  Alternatively, in a static body of water and in the absence of thermal currents, a body of matching density can remain stationary anywhere, though even the slightest disturbance will cause it to move.
• 

  zaveri

  A submarine remains submerged in water at a particular depth by controlling the water content in its ballast tanks. does that principle apply here ?
• 

  Ramani Aswath

  zaveri

  A submarine remains submerged in water at a particular depth by controlling the water content in its ballast tanks. does that principle apply here ?

  To some extent, yes.
  Submarine is an active device. The propeller can keep it at any depth. This is not applicable to passive objects.
• 

  sureshkumargce

  bioramani

  Consider a body of water that has a uniform temperature gradient higher at the surface and progressively colder downward. There will be a corresponding density gradient. Any object with a density in between that at the top and at the bottom will float at a point where the density matches.
  Alternatively, in a static body of water and in the absence of thermal currents, a body of matching density can remain stationary anywhere, though even the slightest disturbance will cause it to move.

  
  In the static body of water (absence of thermal currents)the body has to float at different regions.Is it possible by fixing any small propeller.? What type of calculations have to be made.?
• 

  Ramani Aswath

  sureshkumargce

  In the static body of water (absence of thermal currents)the body has to float at different regions.Is it possible by fixing any small propeller.? What type of calculations have to be made.?

  Size of the propeller will depend on the inertia of the system. The object may float at a given point. However, though it has zero weight its inertia depends on its mass plus drag in the medium. The larger the size, the greater this effect unless streamlined.
• 

  Mohit Kamat

  bioramani

  Consider a body of water that has a uniform temperature gradient higher at the surface and progressively colder downward. There will be a corresponding density gradient. Any object with a density in between that at the top and at the bottom will float at a point where the density matches.
  Alternatively, in a static body of water and in the absence of thermal currents, a body of matching density can remain stationary anywhere, though even the slightest disturbance will cause it to move.

  Sir i'm new to engineering so could you please explain in simpler words, as i don't know what exactly is temperature gradient or thermal currents either. If you could explain your answer with an example??? thanks 😀
• 

  Ramani Aswath

  Let us assume that the top surface of the water is at 60 C. The density is 0.9832 gm/cc.
  Let us assume that the bottom of the water is at 20 C. The density is 0.9982 gm/cc.
  If your object has a density 0.99 gm/cc it will sink to some where near the middle of the water depth where the temperature will be a bit below 40 C.
  
  Here is a video that demonstrates thermal currents:
  
• 

  Mohit Kamat

  thanks sir...appreciate your effort 😀
• 

  ABCD ABCD

  i had heard of a magic trick, in which an egg neither floats nor sink in water. It uses the same principle. Usually a boiled egg submerges completely and a unboiled egg floats on water.
  
  BTW, is the mass of boiled egg more than unboiled one?
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  Ramani Aswath

  Not quite. If an unboiled egg floats it is spoilt.
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  ABCD ABCD

  bioramani

  Not quite. If an unboiled egg floats it is spoilt.

  oh ok... haven't experimented it, but read it somewhere.
• 

  Ramani Aswath

  mreccentric

  BTW, is the mass of boiled egg more than unboiled one?

  The shell is impervious to water. Except for a very small bubble at the top eggs are usually already full. Other than snakes' eggs, which are leathery, birds' eggs are rigid. It is unlikely that boiling leads to an increase in density.
• 

  ABCD ABCD

  bioramani

  The shell is impervious to water. Except for a very small bubble at the top eggs are usually already full. Other than snakes' eggs, which are leathery, birds' eggs are rigid. It is unlikely that boiling leads to an increase in density.

  TY... Then what do you think makes it float or sink? i know that, i can verify this as i have that book... but what makes the boiled egg semi-solidify when boiled?, as you say its impermeable.
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  Ramani Aswath

  mreccentric

  but what makes the boiled egg semi-solidify when boiled?, as you say its impermeable.

  That is a simple matter. The yellow yolk becomes a solid powder on cooking. The white is essentially albumin that gels into a semi solid on cooking.
• 

  ABCD ABCD

  bioramani

  That is a simple matter. The yellow yolk becomes a solid powder on cooking. The white is essentially albumin that gels into a semi solid on cooking.

  does that also mean that there is some chemical change?
• 

  Ramani Aswath

  mreccentric

  does that also mean that there is some chemical change?

  You are right. Boiling is a chemical change. A boiled egg does not become a raw one, no more than a boiled chicken lay eggs.
• 

  ABCD ABCD

  lol... that answers...
  for those who followed my posts, infact, both boiled and unboiled egg sink in water. whereas, a rotten egg floats. Please dont ask my why, as i dont know.
• 

  jishnu nair

  bioramani

  Consider a body of water that has a uniform temperature gradient higher at the surface and progressively colder downward. There will be a corresponding density gradient. Any object with a density in between that at the top and at the bottom will float at a point where the density matches.
  Alternatively, in a static body of water and in the absence of thermal currents, a body of matching density can remain stationary anywhere, though even the slightest disturbance will cause it to move.

• 

  jishnu nair

  bioramani

  Consider a body of water that has a uniform temperature gradient higher at the surface and progressively colder downward. There will be a corresponding density gradient. Any object with a density in between that at the top and at the bottom will float at a point where the density matches.
  Alternatively, in a static body of water and in the absence of thermal currents, a body of matching density can remain stationary anywhere, though even the slightest disturbance will cause it to move.

• 

  CE Designer

  This concept is used to design level sensors for industry.