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From a water tap, liquid comes out from ...

From a water tap, liquid comes out from cylinder. As water moves down, radius of that cylinder decreases. Consider, a very small element of height h and radius R (due to small height radius is assumed to be constant)

This element is given in the diagram. An imaginary cross-section ABCD divides this element in two equal semi cylinder. S is surface tensionof liquid. Now choose correct statement(s)

A

Surface energy of this elementary cylinder is `S[2piRh+2piR^(2)]`

B

Pressure inside the cylinder is more than atmospheric pressure by` (2S)/(R )`

C

Force exerted by one half cylinder on another half cylinder due to surface tension is 2Sh.

D

Surface energy of this elementary cylinder is `Sxx2piRh`

Text Solution

Verified by Experts

The correct Answer is:
C, D
`"Surface energy" = "free surface area" xx "surface tension"`
for a cylindrical surface excess pressure is `(S)/(R )`
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