Question

Penguin huddling. To withstand the harsh weather of the Antarctic, emperor penguins huddle in groups (see the figure). Assume that a penguin is a circular cylinder with a top surface area a = 0.436 m2 and height h = 1.13 m. Let Pr be the rate at which an individual penguin radiates energy to the environment (through the top and the sides); thus NPr is the rate at which N identical, well-separated penguins radiate. If the penguins huddle closely to form a huddled cylinder with top surface area Na and height h, the cylinder radiates at the rate Ph. If N = 1021, (a) what is the value of the fraction Ph/NPr and (b) by what percentage does huddling reduce the total radiation loss?

Answer 1