Physics (10th Edition)

Published by Wiley
ISBN 10: 1118486897
ISBN 13: 978-1-11848-689-4

Chapter 6 - Work and Energy - Problems - Page 169: 63


a) $5.48\times10^6J$ b) $1310$ nutritional Calories.

Work Step by Step

a) The total amount of power Lance Armstrong generates is $\overline P=6.5\times75=487.5W$ We have $$\overline P = \frac{W}{t}=\frac{W}{\frac{s}{\Delta v}}=\frac{W\Delta v}{s}$$ $$W=\frac{\overline Ps}{\Delta v}$$ We know $\overline P=487.5W$, the length of the race $s=135km=1.35\times10^5m$ and his average speed $\Delta v=12m/s$, so $$W=5.48\times10^6J$$ b) The amount of nutritional Calories Lance Armstrong consumes is $(5.48\times10^6J)\times(2.389\times10^{-4})=1310$ nutritional Calories.
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