If you don't solve this problem correctly in $3$ tries, you can get a hint.

Calculate the average force a $60\mathrm{.}72$ kg sprinter exerts on the track to accelerate from $\backslash (2\mathrm{.}00\backslash$mathrm$\{$~m$\}/\backslash$mathrm$\{$s$\}\backslash )$ tc $\backslash (8\mathrm{.}73\backslash$mathrm$\{$~m$\}/\backslash$mathrm$\{$s$\}\backslash )$ in a distance of $20\mathrm{.}53$ m $,$ if she encounters a headwind that exerts an average force of against him. N