Bicyclists in the Tour de France do enormous amounts of work during a race. For
ID: 1284508 • Letter: B
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 108-km race in which his average speed is 12.6 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
a)
mass of person , m = 75 kg
distance , d = 134 km
average speed , v = 12.2 m/s
time taken , t = distance/speed
t = 134*1000/12.2
t = 10983.6 s
power = 6.5 * 75 = 487.5 W
work done = power * time
work done = 487.5 * 10983.6
work done = 5.355 *10^6 J
the work done by Lance armstrong is 5.355 *10^6 J
b)
Now , work done = 5.355 *10^6 * 2.389 *10^-4 Cal
Work done = 1279.2 nutritional Calories
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