A75-kg sprinter accelerates from rest to a speed of 11.0 m/s in 5.0 a) calculate the mechanical work done by the sprinter during this time. i know w=0.5mv^2 = 4538 j . b)calculate the average power the sprinter must generate. p=w/t= 908w. c) if the sprinter converts food energy to mechanical energy with an efficiency of 25%, at what average rate is he burning calories? .

A. Work = KE = 0.5mv²
   Substituting the known values,
                                  KE = 0.5(75 kg)(11 m/s)² = 4537.5 J
b. Power = W / t. Substituting,
                                   P = 4537.5 J / 5 s = 907.5 W
c. Only 25% is absorbed. So, the sprinter only absorbed 226.875 J per second which is equal to 54.20 calories per second. 

The equation is
s= d/t

In this case you would have to write it out as:
s= 20/5
Speed = 4