## 5 Application Case
### Analysis of Work by Overcoming Wind Resistance and Wind Environment Influence  
According to Formulas (7), (10), (12), and (14), three training cases were calculated. The three training results for the athlete are listed in Table 2.  
\(r_{w}\) It can be seen from Table 2 that the athlete's sliding distances are similar in training case 1, case 2, and case 3. The athlete's sliding performance is determined according to the sliding time, and the lowest time is the best. The athlete's training performance from high to low is case 2, case 1, and case 3. In the ideal state, the more work this athlete does to overcome aerodynamic drag in static air, the better their performance, and so the sliding time of training case 1 should be less than training case 2. However, the \(r_{w}\) of training case 1 is 6.68%, and the field wind hinders the athlete, while the \(r_{w}\) of training case 2 is \(-5.67\%\), and the field wind supports the athlete. In training case 3, the work to overcome aerodynamic drag in static air is less than that in training case 1, and the \(r_{w}\) is 10.33%. The field wind will hinder the athlete from sliding more, and training case 3 will take longer. In conclusion, the field wind has a great influence on the athlete's performance. The wind resistance energy dissipation ratio shows that the field wind has a promoting effect on the athlete in training case 2, which is one of the factors that resulted in training case 2 having the best performance among the three cases. In addition, the field wind in training case 1 and case 3 has a hindering effect on the athlete, and the field wind in training case 3 has a greater effect on the athlete, which is also the reason the performance of the athlete in training case 3 is worse than that in training case 1. Therefore, the wind resistance energy dissipation ratio is an important indicator to evaluate the impact of field wind on an athlete's performance. When evaluating an athlete's actual performance, the promotion or hindrance of the field wind to the athlete should be considered. For training case 1, the relative speed between the approaching wind and the athlete's movement (\(U\)) and the relative speed between the static air and the athlete's movement (\(-V\)) are shown in Figure 8. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Posture** & \(A\) **(m2)** & \(C_{D}\) & \(C_{D}A\) **(m2)** \\ \hline free uphill & 0.398 & 0.929 & 0.370 \\ free downhill & 0.241 & 0.701 & 0.169 \\ two-step one support & 0.475 & 0.691 & 0.328 \\ free flat & 0.405 & 0.853 & 0.345 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Frontal area, drag coefficient, and drag area for the four athletic postures. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Case** & **1** & **2** & **3** \\ \hline static air work (J) & 11,328.98 & 9961.88 & 11,306.24 \\ field wind work (J) & 10,619.22 & 10,560.39 & 10,247.76 \\ \(r_{w}\) (\%) & 6.68 & \(-5.67\) & 10.33 \\ average velocity & 6.04 & 6.14 & 5.99 \\ (m/s) & 186 & 183 & 188 \\ distance (m) & 1122.66 & 1124.36 & 1125.78 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Three training results for the athlete. Figure 8 shows that the athlete is greatly affected by the field environmental wind during sliding. In stage \(S_{2}\), the difference between \(U\) and \(-V\) is clear, and the maximum difference is 6.00 m/s, which indicates that the field wind has an impact on the speed of the athlete. It can be seen that the relative speed between the approaching wind and the athlete's movement and the relative speed between the static air and the athlete's movement chart can also be used to qualitatively analyse the influence of the field wind on the athlete's speed. In each stage of training case 1, the athlete overcomes aerodynamic drag to do positive and negative work, as well as work in downwind and upwind conditions; the average speed and corresponding work of the athlete in each stage are depicted in Figures 9a,b and 10.