http://en.wikipedia.org/wiki/Surface_tension.

Which takes us to Surface Energy. Related is Gibbs Free Energy, which I barely recall from Crystallography class decades ago.

As I understand it, when dealing with fluids in small, confined spaces, gravity is just another player. Besides the surface energy, there are chemical gradients as well, all part of a physically connected system attempting to equalize, to achieve entropy, creating interesting patterns along the way.

It’s all quite beyond me, a simple prospector and map-maker, but it fills me with awe.

Oh, there’s that guitar bit I like:
[youtube]rk9A_2xi-CA[/youtube]

The “meniscus” must be taken into account when making careful measurements from a burette or graduated cylinder.

“A convex meniscus occurs when the molecules have a stronger attraction to each other (cohesion) than to the material of the container (adhesion). This may be seen between mercury and glass in barometers and thermometers. Conversely, a concave meniscus occurs when the molecules of the liquid attract those of the container’s, causing the surface of the liquid to cave downwards. This can be seen in a glass of water.”

And yes, it is related to capillary action. (read on)

Now the point of this exercise is to demonstrate my (and your?) attitude towards this phenomena: it seems perfectly normal for the liquid surface to be shaped this way.

On the other hand, if you take some water with food coloring in it and dip the end of a capillary tube in it, and watch the liquid climb to the top of the tube, then it seems like you’ve witnessed something miraculous.

But it is just the same thing happening in both cases.

A falling object’s total energy is the sum of its kinetic and potential energy. As it falls, it loses potential but gains kinetic. If its not going as fast as it should be, that energy goes into the surroundings, usually as friction.

That’s how parachutes work, too.

Letting any mass fall unhindered converts gravitational Potential Energy completely to Kinetic Energy of motion, the fact that it is slowed down indicates some of that kinetic energy is being used up, since it won’t reach the speeds necessary to fully convert PE to KE completely. I.e., some energy is unnacounted for.

However, you can slow a mass by providing a force in the opposite direction (like dropping a ball bearing into a viscous fluid). In this case, some of the PE is lost to friction, i.e., heat, and is dissipated in the fluid. My guess is the electrical forces that slow the magnet down generate heat in the copper pipe and in the magnet itself. IOTW, you don’t use energy to slow it down, but some the PE used up is transferred to heating the metal and is not transferred to the falling body so it can’t speed up. The magnetic field interacting with the metal pipe acts as the viscous fluid, draining KE out of the system.

As for the capillary action, that is caused by the electrical forces in the water molecules. Water exists as a bunch of OH- and H+ ions and H2O molecules flying around together, briefly associating into the complete molecule and then disassociating again. That’s why its such a good solvent. These flying ions bump into other matter and wedge into them and break them up into smaller pieces.

Somehow, (not clear exactly on this), the ions interact electrically with atoms in the fibers or capillaries and it drags itself along them. The energy to push them along must come from the thermal energy in the water, which cools slightly as the thermal motion pushes the water in one direction. If the capillary is too big, or the fiber mesh too coarse, there isn’t enough surface area interaction to allow enough ions to overcome gravity using only the meager energy in the water.

It should be easy to look this up, but I’m too lazy to do it, and its more fun to guess. My guess is Podrock still remembers enough of his chemistry to judge my answer.

Does slowing the magnet in it’s trip down the tube require energy?

Second question. Where does the energy of capillary action come from. A paper towel lowered vertically on a pool of water draws the water up the fibers. Work is being done to lift the water. What’s the source of the energy?