Practice portal › Mechanical Properties of Fluids › Capillary Rise and Angle of Contact
Asked in NEET 2020 · Capillary rise
Given: m₁=5 g in a tube of radius r; second tube of radius 2r, same water.
Idea: the weight of the raised column is held up by the surface tension pulling along the circle of contact, so the mass follows the circumference, not the area.
2π rT cos θ=mg, so m=(2π rT cos θ)/g.
With T, θ and g fixed, m∝ r.
Check by the other route: h=(2T cos θ)/(rρ g) and m=ρπ r²h, so the r² and the 1/r leave one power of r.
(m₂)/(m₁)=(2r)/r=2
m₂=2×5.0=10.0 g
Reading this solution needs no sign-in. You only sign in to practise against the clock and keep your progress.
Practise this with a timer