Question

The record time for a Tour de France cyclist to ascend the 1100-m-high Alpe d'Huez is 37.5 min. The rider and his bike had a mass of 65 kg. At the average speed of the ride, the metabolic power to ride on level ground would be 700 W. To this, we must add the power to make the climb.

Answer 1

the above answer is close but you need to add it to 700W. Mastering Phys has it at 1900W

Answer 2

given,

height of Alpe d'Huez = 1100-m

time = 37.5 min

mass of the rider and his bike = 65 Kg

the metabolic power to ride = 700 W

U = m g y

U = 65 x 9.8 x 1100

U = 700700 J

since efficiency is 25%

`E_(chem) = (U)/(e)`

`E_(chem) = (700700)/(0.25)`

`E_(chem) = 2802800`

`E_(chem) = (2802800)/(4.19 \time 10^3)`

`E_(chem) =668.9\ cal`

b)
`P = (E_(chem))/(t)`

`P = (2802800)/(37.5* 60\ s)`

P = 1245.68 W