1. The problem statement, all variables and given/known data Could some one help me understand capillary Force? 2. Relevant equations 3. The attempt at a solution If we use a capillary tube sticking in a water cup as an example. The phenomenon will be water level is higher in the capillary tube than that in the water cup. I understand that it is the surface tension force b/t tube and water which balances with the self-weight of the part of the water in the tube above the surrounding water level. But I just don't know why water would go up in the first place? So just to make the question clear, I understand why water is able to stay in a higher level in the tube, but I don't know why it goes there. Thanks for the help!