Mechanical Properties of Fluids

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Question : 7
Total: 31
A vertical off-shore structure is built to withstand a maximum stress of 109 Pa. Is the structure suitable for putting up on top of an oil well in the ocean? Take the depth of the ocean to be roughly 3 km, and ignore ocean currents.
Solution:  
Here, depth of water column,
h=3km=3×103m
density of water,ρ=103kg m3
If P be the pressure exerted by this water column at this depth, then
P=hρg=3×103×103×9.8
=29.4×106Pa
=30×106Pa=3×107Pa
As the structure is put on the sea, sea water will exert upward thrust of 3×107Pa.
Maximum stress which the vertical off-shore structure can withstand =109Pa. (Given)
Then 3×107Pa<109Pa
Thus we conclude that the structure is suitable as the stress applied by it is much lesser than the maximum stress it can withstand.
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