Bicyclists in the Tour de France do enormous amounts of work during a race. For

Question

Bicyclists in the Tour de France do enormous amounts of work during a race. For example, the average power per kilogram generated by Lance Armstrong (m = 75.0 kg) is 6.50 W per kilogram of his body mass. (a) How much work does he do during a 187-km race in which his average speed is 11.9 m/s? (b) Often, the work done is expressed in nutritional Calories rather than in joules. Express the work done in part (a) in terms of nutritional Calories, noting that 1 joule = 2.389 x 10-4 nutritional Calories.

Explanation / Answer

Power output = 6.5 W /kg
Mass of Lance Armstrong = 75 kg

Total Power Output =( Power Output/ kg ) x mass
= 487.5 Watts
Now Length of race = 143 km = 143000 meters
Average speed = 11.3 m/s

Time taken = distance/ average speed
= 143000/11.3
= 12654.867 seconds
a .
Now Work done = Power x Time
= 487.5 x 12654.867
= 6169247.663 Joules or 6169.247 Kilo joules

b. Nutritional Calories = Work done x 2.389 x 10 ^-4
= 1473.833 Nutritional Calories

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