3. Results
3.1. Results analyzed by strain gauges
Fig.3 shows the vertical and tangential forces present on the racket surface as detected by strain gauges
attached to the strings. Solid lines indicate the tangential force, and the thin lines indicate vertical force.
The five figures from top to bottom correspond to incident angles of 20°, 30°, 45°, 60°, and 75°
respectively. These results were obtained using racket A.