What unit is used in MKS system and FPS system​

What statements accurately describe atoms

Which statement best describes the superposition principle? a.) if two in-phase waves arrive simultaneously at a point, their amplitudes add up b.) if two out-of-phase waves arrive simultaneously at a point, their amplitudes add up c.) if two in-phase waves arrive at a point one after another, their amplitudes add up d.) if two out-of-phase waves arrive at a point one after another, their amplitudes adds up

Wind and moving water provide energy. question 1 options: chemical mechanical thermal none of the above