Question

The average adult human burns 2.00 x 10^3 kcal per day in energy. What is this rate in kJ per hour?

a) 2.08 kJ/hr
b) 83.33 kJ/hr
c) 48.00 kJ/hr
d) 0.83 kJ/hr

Answer 1

To convert the average adult human energy expenditure from kcal to kJ per hour, multiply 2.00 x 10^3 kcal by 4.184 to convert to kJ, then divide by 24. None of the provided answers matches the correct calculation, which is approximately 349 kJ/hr.

Step-by-step explanation:

The question is asking how to convert energy expenditure from kilocalories (kcal) to kilojoules (kJ) and then determine the rate of energy burned per hour. Since 1 kcal equals 4.184 kJ, we need to convert 2.00 x 103 kcal to kJ and then divide by the number of hours in a day to get the rate per hour.

First, calculate the total energy burned in kJ using the conversion factor:
2.00 x 103 kcal/day x 4.184 kJ/kcal = 8.368 x 103 kJ/day

Next, divide this by 24 hours to obtain the rate in kJ per hour:
8.368 x 103 kJ/day ÷ 24 hours/day = 348.667 kJ/hour

The correct answer is not listed in the options provided, which suggests a possible error in the answers. The rate of energy expenditure is 348.667 kJ per hour, which can also be written as approximately 349 kJ/hr to two significant figures.