Friction Block and Surface Set

To understand the relation between friction and smoothness of materials. Consists of three wooden blocks measuring approximately 3-15/16″ L x 2- 3/4″ W with hooks. The first block has a polished side, the second has a sandpaper side, and the third has an aluminum side. Complete with polished wooden base measuring 14″ L x 2-3/4″ W.