Coefficient of friction is a measure of the slipperiness between two surfaces: the larger the coefficient of friction, the less slippery the surfaces. For example, pulling a heavy wooden block (large normal force) across the floor requires more force than does pulling a light one (small normal force); and pulling the wooden block along on a surface of rubber (large coefficient of friction) requires more force than pulling the same block along on a surface of ice (small coefficient of friction).