In terms of saving energy, bicycling and walking are far

Chapter 5, Problem 5.67

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In terms of saving energy, bicycling and walking are far more efcient means of transportation than is travel by automobile. For example, when riding at 10.0 mi/h, a cyclist uses food energy at a rate of about 400 kcal/h above what he would use if he were merely sitting still. (In exercise physiology, power is often measured in kcal/h rather than in watts. Here, 1 kcal 1 nutritionists Calorie 4 186 J.) Walking at 3.00 mi/h requires about 220 kcal/h. It is interesting to compare these values with the energy consumption required for travel by car. Gasoline yields about 1.30 108 J/gal. Find the fuel economy in equivalent miles per gallon for a person (a) walking and (b) bicycling.