The average weight of an athlete should be around 60kg so from the information that the athlete can run 100m in 10s, we can calculate that their average speed is 10m/s. Using the kinetic energy formula, Ek = 1/2mv^2 we can calculate the kinetic energy using 60kg as the mass.
(1/2)(60)(10^2) = Ek
Ek= 3000J
