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Question:

A capillary tube of radius r is immersed in water and water rises in it to a height h. The mass of water in the capillary tube is 5g. Another capillary tube of radius 2r is immersed in water. The mass of water that will rise in this tube is:

2.5g

10g

5.0g

20g

Solution:

Given :r1=rh1=hr2=2rUsingrh=constant∴r2h2=r1h1(2r)h2=rh⟹h2=h2Mass of the water in the capillaryM=ρ(πr2h)whereρis the density of the waterGiven : Mass of water that rises in the first capillaryM1=5g∴5=ρπr2h(1)Mass of water that will rise in second capillaryM2=ρ(πr22h2)M2=ρπ(2r)2h2=2×ρπr2h⟹M2=2×5=10g