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

Question

Bicydists in the Tour de France do enormous amounts of work during a race. For example, the average power per kilogram generated by seven-time-winner Lance Armstrong (m - 75.0 ko) is 6.50 W per kilogram of his body mass. (a) How much work does he do during a 110-km race in which his average speed is 13.5 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 104 nutritional Calories nutritional Calories Section 6.7 18.1 points CJ10 6 P064 Notes O Ask Your T You are working out on a rowing machine. Each time you pull the rowing bar (which simulates the "oars") toward you, it moves a distance of 1.1 m in a time of 1.1 s. The readout on the display indicates that the average power you are producing is 82 W. What is the magnitude of the force that you exert on the handle? Additional Materials Section 6.7

Explanation / Answer

Given,

m = 75 kg ; P = 6.5 W/kg ;

a)d = 110 km = 110 x 10^3 m ; v = 13.5 m/s

we know that, v = d/t => t = d/v

t = 110 x 10^3/13.5 = 8148.15 s

We know from the defination of power

P = E/t => E = Pt

E = 6.5 W/kg x 75 kg x 8148.15 s = 3972223.125 J = 3.97 x 10^6 J

Hence, E = 3.97 x 10^6 J

b)1 J = 2.389 x 10^-4 Cal

3.97 x 10^6 J = 948.85 cal

Hence, E = 948.85 Cal

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