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MHT CET · Physics · Mechanical Properties of Fluids

A metal wire of density ' \(e\) ' floats on water surface horizontally. If it is NOT to sink in water, then maximum radius of wire is ( \(\mathrm{T}\) = surface tension of water, \(\mathrm{g}\) = gravitational acceleration)

  1. A \(\frac{\pi \mathrm{eg}}{\mathrm{T}}\)
  2. B \(\frac{\mathrm{T}}{\pi \mathrm{eg}}\)
  3. C \(\sqrt{\frac{2 \mathrm{~T}}{\pi \mathrm{eg}}}\)
  4. D \(\sqrt{\frac{\pi e g}{T}}\)
Verified Solution

Answer & Solution

Correct Answer

(C) \(\sqrt{\frac{2 \mathrm{~T}}{\pi \mathrm{eg}}}\)

Step-by-step Solution

Detailed explanation

The correct option is (C).
There are two free surfaces as shown in the figure:

Consider the force balance per unit length as shown in the diagram above:
\(2 \mathrm{~T}=\mathrm{e} \pi \mathrm{r}^2 \mathrm{~g}\)
Therefore, \(r=\sqrt{\frac{2 \mathrm{~T}}{\pi \mathrm{eg}}}\).
We neglect buoyancy force as it is negligible as compared to surface tension force!