A roof measures 13 m by 65 m and is blacken. If the temperature of the sun’s surface is
6000 K, and the radius of the sun is 7.5*108 m. The distance of the sun from the earth is
1.5*108
km. Calculate how much solar energy is incident on the roof per minute,
assuming that one third of the intensity is lost in passing through the earth’s atmosphere.
Assume the roof is normal to the sun’s rays.