Imagine that you had unlimited time and you needed to get from Washington, D.C., to Cleveland, Ohio. The distance is roughly 600 km (370 miles). For each mode of transportation, calculate how many megajoules of energy you would use. Using the data in Table 34.1, we can determine the following:

If a gallon of gasoline contains 120 MJ, how many gallons of gasoline does it take to make the trip by car?

Examining total joules expended makes it clear that the train is the most energy-efficient means of travel. Driving alone in a car is the least energy-efficient.

Your Turn If you could carpool with three other people who needed to make the same trip, what would the energy expenditure be for each person?