Fish oil in your diet will improve your memory. Independent variable? Dependent variable

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?

When you push downward on a book at rest on a table, you feel an upward force. does this force depend on friction? defend your answer.

If the work required to stretch a spring 3 ft beyond its natural length is 15 ft-lb, how much work is needed to stretch it 27 in. beyond its natural length?