Final answer:
The efficiency of a person on a treadmill could be roughly estimated from their rate of work and oxygen consumption rate, often around 20% during moderate exercise. Consequently, walking on a treadmill can burn approximately 5 kcal per minute, aligned with caloric burn during moderate workouts.
Step-by-step explanation:
The efficiency of a person exercising can be determined by comparing the energy output in work with the energy input from metabolism (in this case, the oxygen consumed). The rate of work output given is 100 watts (W), and the subject is consuming oxygen at the rate of 2.00 liters per minute.
To calculate the efficiency, we would typically need the energy equivalent for the oxygen consumption, which is often given in tables like the referred Table 7.5. The formula for efficiency is (useful energy output / total energy input) × 100. Assuming from the context provided, efficiency while exercising tends to be around 20%, and since walking on a treadmill is a form of exercise, we could estimate the calorie consumption per minute accordingly.
For a rough estimate of calories burned per minute, we take that a moderate workout might burn between 50-100 kcal over 20 minutes. This translates to 2.5-5 kcal per minute. Considering that 1 kcal is equal to 4.184 kilojoules (kJ), a power output of 100 W (which is 0.1 kJ/s), and assuming 20% efficiency, a person would be burning approximately 5 kcal per minute walking on a treadmill. This aligns with the aforementioned range for a moderate workout.