Sunny - solar radiation on tilted book · Physics Brawl 2015 #FoL.10
Physics · optics
Problem
Mirek decided to do something for his health, so he took his school books outdoor for fresh air. The sky was clear and the sun was exactly at the south, α=50° above the horizon. If Mirek places his book horizontally, then it receives radiation power P from the sun. Determine the lowest angle β by which Mirek must tilt the book towards himself (he looks at it from the north) so that the incident radiation power drops to P/2.