Cuales son las cualidades del sonido: intensidad, timbre y tono

An initially unpolarized light if intensity 500 w/m^2 passes through four polarizers. the transmission axis between adjacent polarizers is 45∘. what percentage of the initial intensity is transmitted by the system?

Ascientist wants to test ways to reduce pollution in lake . what is the bestway of doing this

How does the motion of an airplane compare to the motion of a rocket ?