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CBSE - XI Science - Physics - Mechanical Properties of Fluids

Why does a needle floats on water but sink when some impurities are added.

Asked by Arun Iyer 19th February 2011, 5:29 PM
Answered by Expert


Dear student

The surface tension of clean water being higher than that of water mixed with impurities, it can support the weight of a needle due to its surface tension. By addition of impurity, the surface tension of water reduces, thereby resulting in the sinking of the needle.

Hope this clarifies your doubt.
Answered by Expert 20th February 2011, 11:47 AM

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