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**1. Homework Statement**

The intensity of the suns' radiation just outside the earth's atmosphere is approximately

8x10^4 joules/m^2*min

Approximately what force does this radiation exert on the Echo II reflecting satellite ballon? Echo II is a spherical shell of radius 20.4 m. Its skins consists of a layer of Mylar plastic, 9x10^-6 m thick, between two layers of aluminum, each 4.5x10^-6 m thick. The density of Mylar is 10^3 kg/m^3; of aluminum 2.7x10^3 kg/m^3..

This is problem 1-2 out of Special Relativity by A.P. French and the solution is 5.76x10^-3 N

Also the information on the densities are for the preceding question about the gravitational pull on the shell. I assume the force the radation exerts is independent of its mass.

**2. Homework Equations**

**3. The Attempt at a Solution**

8x10^4 joules/m^2*min / 60 = 1333 joules/m^2*sec

1333 joules/m^2*sec * 4(pi)(20.4m)^2 = 6972827.7 joules/sec

Here is where things break down. I tried dividing by the speed of light

(6972827.7 joules/sec) / (3*10^8 m/sec) = .0232426 N