Question

A long capillary tube of mass  gram, radius 2 mm and negligible thickness, is partially immersed in a liquid of surface tension 0.1N/m. Take angle of contact zero and neglect buoyant force of liquid. The force required to hold the tube vertically will be (g = 10 m/s2 )

Answer 1

Consider the formula  

F = mg + 2 S(2π r )  

Assumed,  

m = π gm, r = 2 mm = 2 × 10-3 m, S = 0. 1N/m , g = 10 m/  s 2

F = 10π + 2 × 0. 1(2 × π × 2 × 10 ) −3

F = 10. 8π mN