A small person with a surface area of about $1.0 \mathrm{~m}^{2}$ must (by the Stefan-Boltzmann law) radiate energy at a rate that would require eating 11,000 food calories a day if they are naked in a vacuum in deep space. Which do you think is the most important reason that someone sitting in a normal room requires less than 2000 calories a day?

Question

A small person with a surface area of about $1.0 \mathrm{~m}^{2}$ must (by the Stefan-Boltzmann law) radiate energy at a rate that would require eating 11,000 food calories a day if they are naked in a vacuum in deep space. Which do you think is the most important reason that someone sitting in a normal room requires less than 2000 calories a day?

Quizplus · Accepted Answer

The most important reason someone in a normal room requires less than 2000 calories a day, compared to the scenario of being naked in a vacuum, is that the person absorbs radiation from the room. This significantly reduces the net loss of energy through radiation, as the Stefan-Boltzmann law considers both emission and absorption. In a normal room, the walls, objects, and air are at a similar temperature to the human body, leading to a balance between the energy radiated by the body and the energy absorbed from the surroundings.

A Small Person with a Surface Area of About 1.0 m21.0 \mathrm{~m}^{2}1.0 m2

A Small Person with a Surface Area of About $1.0 \mathrm{~m}^{2}$