Question

When a glass capillary tube is dipped at one end in water, water rise in the tube. The gravitational potential energy is thus increased. Is it a violation of conservation of energy?

Answer 1

No. It is not a violation of the conservation of energy.  It can be explained due to two reasons:-       

1. The gravitational potential energy of the part of the water that rises in the tube increases but simultaneously the level of the rest of the water goes down depending on the open surface area of the water. So some of the increased P.E. is compensated by the decrease in this water level.         

2. The work done by the vertical component of the net force due to surface tension around the meniscus is stored as the net increase in the gravitational potential energy of the water in the tube.