# "Gravityless" Capillary tube

## Homework Statement

A 20 cm long capillary tube is dipled in water.The water rises up to 8cm .if the entire arrangement is put in a freely falling elevator ,the lenght of the water column is

A)10cm

B)8cm

C)20cm

D)4cm

## Homework Equations

Its a theoretical sum

## The Attempt at a Solution

Okay...since this is a freely falling elevator ,the reletive accelaration will be zero and hence i feel the fluid will maintain its orignal height of 8cm

But alas ,the book says its 20cm and have give the reason that since its "gravityless" ie :rel accelaration 0, it will occupy full capillary tube.

[Edit 1 -fixed a typo
Edit 2 - i wrote about what i did in Edit 1]

Last edited:

Chandra Prayaga
What are the forces acting on the column of water in the capillary before you put it in the elevator? What force is pulling the water up the capillary against gravity?

Navin
What are the forces acting on the column of water in the capillary before you put it in the elevator? What force is pulling the water up the capillary against gravity?

Oh !!! I think i got it !!!
Case 1
Alright ,so before we put the fluid in the elevator we have forces of adhesion pulling water up the capillary tube,but one it reaches a certain hieght ,force of gravity dominates and hence it cant go further

Case 2
During free fall there is nothing to stop the liquid from rising ,that is ,due to adhesion the liquid continues to rise until it occupies full cappilary tube !!!

Hence the answer should be 20 cm right ???