Tech Facts - Friction Surface

This is one of the in-depth videos on friction and the second of a small series about this subject. How is friction affected by the amount of surface area?

Links to the general and other in-depth videos:

General:    • Tech Facts - Friction General  
Material:    • Tech Facts - Friction Material  
Coefficient:    • Tech Facts - Friction Coefficient  
Bonding:    • Tech Facts - Friction Bonding