cohesive forces

Necesary materials:
big bowl, water and tablet's packaging.

To make this experiments pour some water into the bowl. From the tablet's packaging cut out the places where tablets were and put them carefully onto the water. Observe their movement. At first we will see interaction of just two elements and later the others.

The elements cut of the tablet's packaging represents molecules, which attract each other. Among the particles we can observe forces of the molecules interaction. They can attract each other and therefore they are also called cohesive forces. In fact the interaction among the molecules is the effect of the surface tension of liquid.
You see that one of pieces haven't attracted each other. It is because it is partially submerged.