Fig. 1: Measurement of friction between fingertip and baseball leather sheet.
From: Effect of grip-enhancing agents on sliding friction between a fingertip and a baseball
a, b Experimental setup for MLB ball leather sheet with seam (a) and that for MLB ball without seam (b). c–e Finger conditions; no application (c), rosin application (d), and sticky substance application (e). f An example of time series of the normal force (Fz), the horizontal force (Fy), and the friction coefficient µ (Fy/Fz) during a single trial in which an index fingertip is slid with five different levels of the normal force. g The relation between horizontal (Fy_μmax) and normal forces (Fz_μmax) at the maximum friction coefficient µmax. Using this plot, we calculated the mean µmax as the slope of the least square regression square line (e.g., 0.778 in g). h The relation between the µmax and Fz_μmax. Using this plot, we evaluated the dynamic change of friction across the applied normal force. The data in g and h were collected from three trials at five force levels (15 slides) under no application conditions for MLB ball without seam.
