Separating Notebooks

We interleave the pages of notebooks to see how hard it is to pull them apart. As the amount of interleaving increases, we see that the force required to separate them also increases. This is because the friction between the notebooks is increasing. Physics - Forces - Learning Points. Friction depends on the surface area in contact. Frictional force and area seem to be directly proportional. Viewing the surface of a material like paper using a microscope shows how surfaces make contact in many millions of places. A Twig Experiment Film. Let students experience real experiments in lab conditions anywhere, from setup, method all the way through to analysis and real-world application.