Friction blocks surfaces rvfm ph10572f p these friction blocks and surfaces can be used to illustrate the concept that friction depends on the nature and smoothness of materials p p the kit consists of a glass mirror with sandpaper affixed to one side plus two wooden blocks one plain and one with a mirror cemented to one face both static and sliding frictional forces between different surfaces can be compared and contrasted using this kit p rvfm friction blocks surfaces