ITF

39 4. COURT PACE (ITF CS 01/02) The ITF Court Pace Rating (CPR) measures the effect of ball-surface interaction. This concept includes: friction, which primarily determines the reduction in the horizontal component of post-impact ball velocity, and vertical restitution, which determines the time between successive bounces. CPR is derived from a theoretical model of ball/surface impact that assumes that the ball and surface are rigid during the impact and that the ball slides throughout its contact with the surface. These assumptions necessitate that the ball impacts the surface with negligible spin and at a particular speed and angle. Apparatus Test apparatus consists of: A means of projecting a ball at the specified speed and angle onto the surface with spin of no more than 3 rev/s 1 , such as a compressed air-powered ball cannon. A means of monitoring the trajectory of the ball before and after impact such that its horizontal and vertical speeds can be measured with a maximum uncertainty of ± 0.05 m/s (see Figure 2). A minimum of three high-specification balls (see Table 1). Note: Angle of travel can be deduced from the vertical and horizontal speeds. Figure 2. Test apparatus for measuring court pace. 1 The spin rate of the ball can be checked using a high-speed video camera or stroboscope photography.

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