Question

1. Let’s say that an average person consumes about 2000 calories per day over their entire lifetime. A calorie (Cal) is a unit of energy and one Cal equals 4186 ? (Joules). For someone who lives to a ripe age of 100 years, how much energy, in J will they require? What is their average power output in ?/? = ????? (abbreviated ?)?

b) Given the total energy a person requires that you calculated above, use Einstein’s equation to determine how much mass has to be converted to energy to account for this much energy. If a person eats on average 0.5 ?? of food per day, what fraction of that total food mass was actually converted to energy (that is, what is the efficiency of the human body as a generator of energy for a given input mass of food)? Recall that the comparable efficiency of the Sun—which is essentially a gigantic nuclear reactor—is 0.007.

Answer 1