Time needed for ice in an ocean to melt

  • Thread starter adhominem
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  • #1
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Okay, so there is a large floating mass of ice in the sea.
We know the time it takes to melt: it's 168 hours, or 604800 seconds.

The temperature of the air is 25 degrees Celsius.

The surface area of the ice is 2408 km^2. Temperature of the ice is -1 degrees Celsius.

Thermal conductivity of air is 0.024, right?

How do I calculate the mass of the ice?
 

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  • #2
haruspex
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I assume the water is also at -1C, and that as the surface ice melts it is presumed to run off instantly.
You seem to be missing a piece of data, the effective thickness of the boundary layer of air.
 
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How do I get boundary thickness?
 
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haruspex
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How do I get boundary thickness?
There is no standard value. Typically it depends on the windspeed. By itself the "25C" information is useless - you need to know how far above the ice it is at 25 C. If you ignore the boundary layer and take the 25C as being directly in contact with the ice then you get the silly answer that it melts instantly.

Are you sure you have quoted all the information exactly as given to you?
 
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There is no standard value. Typically it depends on the windspeed. By itself the "25C" information is useless - you need to know how far above the ice it is at 25 C. If you ignore the boundary layer and take the 25C as being directly in contact with the ice then you get the silly answer that it melts instantly.

Are you sure you have quoted all the information exactly as given to you?
Windspeed is 9m/s.

Oh, the ice itself is -1 degrees celsius. The 25 degree temperature is 500 metres above sea level.
 
  • #6
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You need to estimate the heat transfer coefficient with a 9m/s wind speed. I guess you also need to assume that only a small fraction of the ice is in contact with the air (archemides). This problem is a test to see if you know how to approach a heat transfer calculation by making reasonable assumptions. By the way, this is a homework problem, correct?
 

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