Answer to Question #250042 in Mechanics | Relativity for John

Question

 Based on the inverse square law, at distance d = 5 m: (a) what is the total area over which energy is dispersed? (b) what is the fraction of the total area represented by the total dispersal area compared to d = 1? 

Answer 1

a)

sphere surface area:

$A=4\pi d^2=4\pi\cdot 5^2=100\pi=314$ m²

b)

the fraction:

$\frac{4\pi\cdot 1^2}{4\pi\cdot 5^2}=\frac{1}{25}$