(a) What is the efficiency of an out-of-condition professor who does 2.10×105 J of useful work while metabolizing 500 kcal of food energy? (b) How many food calories would a well-conditioned athlete metabolize in doing the same work with an efficiency of 20%?

Step-by-step solution Step 1 of 5 Ratio of output energy to the input energy is known as efficiency, Here is the efficiency, is the output energy and is the input energy. Step 2 of 5 (a) Use the above formula, Step 3 of 5 Substitute for and for . Therefore, the efficiency of the professor is .