Final answer:
Jessie's metabolic energy usage can be expressed in Calories or joules, with 1 Calorie being equivalent to 4.184 kilojoules. A daily intake of 2000 kcal translates to 8.368×106 joules, which can further be converted to kilowatt-hours for comparison with household electricity usage.
Step-by-step explanation:
Metabolic energy used by Jessie to complete a course can be expressed in multiple units, but the most appropriate ones from the given choices are either Calories or joules. Since 1 Calorie equals 4.184 kilojoules, we can easily convert Calories to joules. As an example: If Jessie consumes 2000 kcal daily, to convert this to joules, first convert kilocalories to calories and then to joules, which results in 2000 kcal × 1000 (to get calories) × 4.184 (to get joules).
In terms of converting to kilowatt-hours (kWh), we know that 1 kWh equals 3.6×106 joules. For instance, if Jessie's metabolic energy intake is equivalent to 2000 kcal, this translates roughly to 2000 × 1000 × 4.184 J / 3.6×106, which gives the energy in kWh. Comparatively, the average American household uses about 30 kWh of electricity daily, indicating Jessie's metabolic intake is much less in energy terms.