JEE Main · 2005 · 08 May 2005 · Offline · Fluid Mechanics

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A 20 cm long capillary tube is dipped in water. The water rises up to 8 cm. If the entire arrangement is put in a freely falling elevator the length of water column in the capillary tube will be

(A)8 cm
(B)10 cm
(C)4 cm
(D)20 cm✓ Correct

Answer: (D)

Solution

Capillary rise arises from surface tension lifting the water against its own weight. In a freely falling lift the effective gravity is zero, so the water column is weightless and surface tension meets no opposing weight. The water is therefore drawn up the whole tube and simply fills its entire length of

20

cm.

JEE Main · 2005 · 08 May 2005 · Offline · Single correct option

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