Figure 2.
Steady-state contact forces increased in magnitude as a function of drag speed over drag distances of 10−3 mm (open circles), 10−2 mm (filled circles), 10−1 mm (open squares), 100 mm (filled squares), and 101 mm (open triangles). (a) Friction forces increased 3.3× over the velocity range. (b) Adhesion forces increased 10.3× over the test velocity range. Line fits are Fshear = (0.018 N)(1 + v/(1.11 × 103 mm s−1))−1 × sinh−1(v/(0.972 mm s−1)) + 0.044 N (R2 = 0.99) and Fnormal =−(0.009 N)(1 + v/(1.11 × 103 mm s−1))−1 sinh−1(v/(0.751 mm s−1)) − 0.009 N (R2 = 0.99).