Using energy considerations, calculate the average force a 62.0 kg sprinter exerts backward on the track to accelerate from 2.00 to 5.00 m/s in a distance of 25.0 m, if he encounters a headwind that exerts an average force of 30.0 N against him.

Answer 1

Work = The change in kinetic energy:
Work = KE2-KE1 = 0.5*M*V2^2 - 0.5*M*V1^2
= 31*5^2 - 31*2^2 = 651 J.

Work = (Fe-30)*d = 651.
(Fe-30)*25 = 651.
25Fe - 750 = 651.
25Fe = 1401.
Fe = 56 N. = Force exerted.