A 75-kg sprinter accelerates from rest to a speed of 11.0 m/s in 5.0 s.?
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?
(I dont get this question)

Thank You!

Question

A 75-kg sprinter accelerates from rest to a speed of 11.0 m/s in 5.0 s.?
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?
(I dont get this question)

Thank You!

anonymous · Answer

calory is a form of energy. 
rate of burning calory is power.

efficiency=25% (given)
power emitted or generated= 908W

therefore,
power generated/(rate of burning of calory)=25/100

so, rate of burning of calory= 4*908 =  3632W