ABSTRACT
This chapter describes the properties of fluids. Anything that flows can be considered a fluid. Capillary action is the action of fluids rising up through narrow tubes and is the reason why some paper towels are so absorbent. Capillary action arises from the adhesion between the fluid and the wall of the tube. Fluid will rise upward against the force of gravity until a balance is struck between adhesion, cohesion, and gravity. Whether a fluid beads up on a surface or disperses depends on the relative strength of the cohesion between the molecules of the fluid compared with the adhesion between the fluid and the surface. The hydrometer contains a vial sealed with air and a weight, and the combination has the same density as water. As the solution is drawn into the hydrometer, the vial will float to some level where the buoyancy force balances out the weight of the vial.
