For Exercises 16–20, refer to the following. Energy can be thought of as power applied over time. Power can be measured in kilowatts and energy in kilowatt-hours (kWh), where 1 kilowatt-hour is 1000 watts of power exerted for 1 hour. For example, a 40-watt bulb burning for 24 hours consumes 960 watt-hours ≈ 1 kWh. Other forms of energy, such as food or gasoline, can be converted to an equivalent in kWh.
16. An average adult in the U.S. consumes about 2500 food calories per day; one food calorie has the same energy as . A gallon of gasoline contains 33.7 kWh of energy. Compare the energy consumption of a car that gets 30 mpg and is driven about 30 mi/day (say, 12,000 mi/yr) with the food energy consumption of its driver. What do you conclude?